diff --git a/moto/ec2/models.py b/moto/ec2/models.py
index 0ea10555c..2150f2567 100644
--- a/moto/ec2/models.py
+++ b/moto/ec2/models.py
@@ -11,6 +11,7 @@ from .utils import (
     random_reservation_id,
     random_security_group_id,
     random_snapshot_id,
+    random_spot_request_id,
     random_subnet_id,
     random_volume_id,
     random_vpc_id,
@@ -306,11 +307,12 @@ class SecurityGroupBackend(object):
         self.groups = {}
         super(SecurityGroupBackend, self).__init__()
 
-    def create_security_group(self, name, description):
+    def create_security_group(self, name, description, force=False):
         group_id = random_security_group_id()
-        existing_group = self.get_security_group_from_name(name)
-        if existing_group:
-            return None
+        if not force:
+            existing_group = self.get_security_group_from_name(name)
+            if existing_group:
+                return None
         group = SecurityGroup(group_id, name, description)
         self.groups[group_id] = group
         return group
@@ -333,6 +335,11 @@ class SecurityGroupBackend(object):
             if group.name == name:
                 return group
 
+        if name == 'default':
+            # If the request is for the default group and it does not exist, create it
+            default_group = ec2_backend.create_security_group("default", "The default security group", force=True)
+            return default_group
+
     def authorize_security_group_ingress(self, group_name, ip_protocol, from_port, to_port, ip_ranges=None, source_group_names=None):
         group = self.get_security_group_from_name(group_name)
         source_groups = []
@@ -496,9 +503,77 @@ class SubnetBackend(object):
         return self.subnets.pop(subnet_id, None)
 
 
+class SpotInstanceRequest(object):
+    def __init__(self, spot_request_id, price, image_id, type, valid_from,
+                 valid_until, launch_group, availability_zone_group, key_name,
+                 security_groups, user_data, instance_type, placement, kernel_id,
+                 ramdisk_id, monitoring_enabled, subnet_id):
+        self.id = spot_request_id
+        self.state = "open"
+        self.price = price
+        self.image_id = image_id
+        self.type = type
+        self.valid_from = valid_from
+        self.valid_until = valid_until
+        self.launch_group = launch_group
+        self.availability_zone_group = availability_zone_group
+        self.key_name = key_name
+        self.user_data = user_data
+        self.instance_type = instance_type
+        self.placement = placement
+        self.kernel_id = kernel_id
+        self.ramdisk_id = ramdisk_id
+        self.monitoring_enabled = monitoring_enabled
+        self.subnet_id = subnet_id
+
+        self.security_groups = []
+        if security_groups:
+            for group_name in security_groups:
+                group = ec2_backend.get_security_group_from_name(group_name)
+                if group:
+                    self.security_groups.append(group)
+        else:
+            # If not security groups, add the default
+            default_group = ec2_backend.get_security_group_from_name("default")
+            self.security_groups.append(default_group)
+
+
+class SpotRequestBackend(object):
+    def __init__(self):
+        self.spot_instance_requests = {}
+        super(SpotRequestBackend, self).__init__()
+
+    def request_spot_instances(self, price, image_id, count, type, valid_from,
+                               valid_until, launch_group, availability_zone_group,
+                               key_name, security_groups, user_data,
+                               instance_type, placement, kernel_id, ramdisk_id,
+                               monitoring_enabled, subnet_id):
+        requests = []
+        for index in range(count):
+            spot_request_id = random_spot_request_id()
+            request = SpotInstanceRequest(
+                spot_request_id, price, image_id, type, valid_from, valid_until,
+                launch_group, availability_zone_group, key_name, security_groups,
+                user_data, instance_type, placement, kernel_id, ramdisk_id,
+                monitoring_enabled, subnet_id
+            )
+            self.spot_instance_requests[spot_request_id] = request
+            requests.append(request)
+        return requests
+
+    def describe_spot_instance_requests(self):
+        return self.spot_instance_requests.values()
+
+    def cancel_spot_instance_requests(self, request_ids):
+        requests = []
+        for request_id in request_ids:
+            requests.append(self.spot_instance_requests.pop(request_id))
+        return requests
+
+
 class EC2Backend(BaseBackend, InstanceBackend, TagBackend, AmiBackend,
                  RegionsAndZonesBackend, SecurityGroupBackend, EBSBackend,
-                 VPCBackend, SubnetBackend):
+                 VPCBackend, SubnetBackend, SpotRequestBackend):
     pass
 
 
diff --git a/moto/ec2/responses/spot_instances.py b/moto/ec2/responses/spot_instances.py
index 0ace72dfd..759914989 100644
--- a/moto/ec2/responses/spot_instances.py
+++ b/moto/ec2/responses/spot_instances.py
@@ -1,12 +1,25 @@
 from jinja2 import Template
 
 from moto.ec2.models import ec2_backend
-from moto.ec2.utils import resource_ids_from_querystring
 
 
 class SpotInstances(object):
+    def _get_param(self, param_name):
+        return self.querystring.get(param_name, [None])[0]
+
+    def _get_int_param(self, param_name):
+        value = self._get_param(param_name)
+        if value is not None:
+            return int(value)
+
+    def _get_multi_param(self, param_prefix):
+        return [value[0] for key, value in self.querystring.items() if key.startswith(param_prefix)]
+
     def cancel_spot_instance_requests(self):
-        raise NotImplementedError('SpotInstances.cancel_spot_instance_requests is not yet implemented')
+        request_ids = self._get_multi_param('SpotInstanceRequestId')
+        requests = ec2_backend.cancel_spot_instance_requests(request_ids)
+        template = Template(CANCEL_SPOT_INSTANCES_TEMPLATE)
+        return template.render(requests=requests)
 
     def create_spot_datafeed_subscription(self):
         raise NotImplementedError('SpotInstances.create_spot_datafeed_subscription is not yet implemented')
@@ -18,10 +31,186 @@ class SpotInstances(object):
         raise NotImplementedError('SpotInstances.describe_spot_datafeed_subscription is not yet implemented')
 
     def describe_spot_instance_requests(self):
-        raise NotImplementedError('SpotInstances.describe_spot_instance_requests is not yet implemented')
+        requests = ec2_backend.describe_spot_instance_requests()
+        template = Template(DESCRIBE_SPOT_INSTANCES_TEMPLATE)
+        return template.render(requests=requests)
 
     def describe_spot_price_history(self):
         raise NotImplementedError('SpotInstances.describe_spot_price_history is not yet implemented')
 
     def request_spot_instances(self):
-        raise NotImplementedError('SpotInstances.request_spot_instances is not yet implemented')
+        price = self._get_param('SpotPrice')
+        image_id = self._get_param('LaunchSpecification.ImageId')
+        count = self._get_int_param('InstanceCount')
+        type = self._get_param('Type')
+        valid_from = self._get_param('ValidFrom')
+        valid_until = self._get_param('ValidUntil')
+        launch_group = self._get_param('LaunchGroup')
+        availability_zone_group = self._get_param('AvailabilityZoneGroup')
+        key_name = self._get_param('LaunchSpecification.KeyName')
+        security_groups = self._get_multi_param('LaunchSpecification.SecurityGroup.')
+        user_data = self._get_param('LaunchSpecification.UserData')
+        instance_type = self._get_param('LaunchSpecification.InstanceType')
+        placement = self._get_param('LaunchSpecification.Placement.AvailabilityZone')
+        kernel_id = self._get_param('LaunchSpecification.KernelId')
+        ramdisk_id = self._get_param('LaunchSpecification.RamdiskId')
+        monitoring_enabled = self._get_param('LaunchSpecification.Monitoring.Enabled')
+        subnet_id = self._get_param('LaunchSpecification.SubnetId')
+
+        requests = ec2_backend.request_spot_instances(
+            price=price,
+            image_id=image_id,
+            count=count,
+            type=type,
+            valid_from=valid_from,
+            valid_until=valid_until,
+            launch_group=launch_group,
+            availability_zone_group=availability_zone_group,
+            key_name=key_name,
+            security_groups=security_groups,
+            user_data=user_data,
+            instance_type=instance_type,
+            placement=placement,
+            kernel_id=kernel_id,
+            ramdisk_id=ramdisk_id,
+            monitoring_enabled=monitoring_enabled,
+            subnet_id=subnet_id,
+        )
+
+        template = Template(REQUEST_SPOT_INSTANCES_TEMPLATE)
+        return template.render(requests=requests)
+
+
+REQUEST_SPOT_INSTANCES_TEMPLATE = """<RequestSpotInstancesResponse xmlns="http://ec2.amazonaws.com/doc/2013-06-15/">
+  <requestId>59dbff89-35bd-4eac-99ed-be587EXAMPLE</requestId>
+  <spotInstanceRequestSet>
+    {% for request in requests %}
+    <item>
+      <spotInstanceRequestId>{{ request.price }}</spotInstanceRequestId>
+      <spotPrice>{{ request.price }}</spotPrice>
+      <type>{{ request.type }}</type>
+      <state>{{ request.state }}</state>
+      <status>
+        <code>pending-evaluation</code>
+        <updateTime>YYYY-MM-DDTHH:MM:SS.000Z</updateTime>
+        <message>Your Spot request has been submitted for review, and is pending evaluation.</message>
+      </status>
+      <availabilityZoneGroup>{{ request.availability_zone_group }}</availabilityZoneGroup>
+      <launchSpecification>
+        <imageId>{{ request.image_id }}</imageId>
+        <keyName>{{ request.key_name }}</keyName>
+        <groupSet>
+          {% for group in request.security_groups %}
+          <item>
+            <groupId>{{ group.id }}</groupId>
+            <groupName>{{ group.name }}</groupName>
+          </item>
+          {% endfor %}
+        </groupSet>
+        <kernelId>{{ request.kernel_id }}</kernelId>
+        <ramdiskId>{{ request.ramdisk_id }}</ramdiskId>
+        <subnetId>{{ request.subnet_id }}</subnetId>
+        <instanceType>{{ request.instance_type }}</instanceType>
+        <blockDeviceMapping/>
+        <monitoring>
+          <enabled>{{ request.monitoring_enabled }}</enabled>
+        </monitoring>
+        <ebsOptimized>{{ request.ebs_optimized }}</ebsOptimized>
+        <PlacementRequestType>
+          <availabilityZone>{{ request.placement }}</availabilityZone>
+          <groupName></groupName>
+        </PlacementRequestType>
+      </launchSpecification>
+      <launchGroup>{{ request.launch_group }}</launchGroup>
+      <createTime>YYYY-MM-DDTHH:MM:SS.000Z</createTime>
+      {% if request.valid_from %}
+      <validFrom>{{ request.valid_from }}</validFrom>
+      {% endif %}
+      {% if request.valid_until %}
+      <validUntil>{{ request.valid_until }}</validUntil>
+      {% endif %}
+      <productDescription>Linux/UNIX</productDescription>
+    </item>
+    {% endfor %}
+ </spotInstanceRequestSet>
+</RequestSpotInstancesResponse>"""
+
+DESCRIBE_SPOT_INSTANCES_TEMPLATE = """<DescribeSpotInstanceRequestsResponse xmlns="http://ec2.amazonaws.com/doc/2013-06-15/">
+  <requestId>59dbff89-35bd-4eac-99ed-be587EXAMPLE</requestId>
+  <spotInstanceRequestSet>
+    {% for request in requests %}
+    <item>
+      <spotInstanceRequestId>{{ request.id }}</spotInstanceRequestId>
+      <spotPrice>{{ request.price }}</spotPrice>
+      <type>{{ request.type }}</type>
+      <state>{{ request.state }}</state>
+      <status>
+        <code>pending-evaluation</code>
+        <updateTime>YYYY-MM-DDTHH:MM:SS.000Z</updateTime>
+        <message>Your Spot request has been submitted for review, and is pending evaluation.</message>
+      </status>
+      {% if request.availability_zone_group %}
+        <availabilityZoneGroup>{{ request.availability_zone_group }}</availabilityZoneGroup>
+      {% endif %}
+      <launchSpecification>
+        <imageId>{{ request.image_id }}</imageId>
+        {% if request.key_name %}
+          <keyName>{{ request.key_name }}</keyName>
+        {% endif %}
+        <groupSet>
+          {% for group in request.security_groups %}
+          <item>
+            <groupId>{{ group.id }}</groupId>
+            <groupName>{{ group.name }}</groupName>
+          </item>
+          {% endfor %}
+        </groupSet>
+        {% if request.kernel_id %}
+        <kernelId>{{ request.kernel_id }}</kernelId>
+        {% endif %}
+        {% if request.ramdisk_id %}
+        <ramdiskId>{{ request.ramdisk_id }}</ramdiskId>
+        {% endif %}
+        {% if request.subnet_id %}
+        <subnetId>{{ request.subnet_id }}</subnetId>
+        {% endif %}
+        <instanceType>{{ request.instance_type }}</instanceType>
+        <blockDeviceMapping/>
+        <monitoring>
+          <enabled>{{ request.monitoring_enabled }}</enabled>
+        </monitoring>
+        <ebsOptimized>{{ request.ebs_optimized }}</ebsOptimized>
+        {% if request.placement %}
+          <PlacementRequestType>
+            <availabilityZone>{{ request.placement }}</availabilityZone>
+            <groupName></groupName>
+          </PlacementRequestType>
+        {% endif %}
+      </launchSpecification>
+      {% if request.launch_group %}
+        <launchGroup>{{ request.launch_group }}</launchGroup>
+      {% endif %}
+        <createTime>YYYY-MM-DDTHH:MM:SS.000Z</createTime>
+      {% if request.valid_from %}
+        <validFrom>{{ request.valid_from }}</validFrom>
+      {% endif %}
+      {% if request.valid_until %}
+        <validUntil>{{ request.valid_until }}</validUntil>
+      {% endif %}
+      <productDescription>Linux/UNIX</productDescription>
+    </item>
+    {% endfor %}
+  </spotInstanceRequestSet>
+</DescribeSpotInstanceRequestsResponse>"""
+
+CANCEL_SPOT_INSTANCES_TEMPLATE = """<CancelSpotInstanceRequestsResponse xmlns="http://ec2.amazonaws.com/doc/2013-06-15/">
+  <requestId>59dbff89-35bd-4eac-99ed-be587EXAMPLE</requestId>
+  <spotInstanceRequestSet>
+    {% for request in requests %}
+    <item>
+      <spotInstanceRequestId>{{ request.id }}</spotInstanceRequestId>
+      <state>cancelled</state>
+    </item>
+    {% endfor %}
+  </spotInstanceRequestSet>
+</CancelSpotInstanceRequestsResponse>"""
diff --git a/moto/ec2/utils.py b/moto/ec2/utils.py
index 7dfa3ea03..a86ed64c5 100644
--- a/moto/ec2/utils.py
+++ b/moto/ec2/utils.py
@@ -10,6 +10,10 @@ def random_id(prefix=''):
     return '{}-{}'.format(prefix, instance_tag)
 
 
+def random_ami_id():
+    return random_id(prefix='ami')
+
+
 def random_instance_id():
     return random_id(prefix='i')
 
@@ -18,14 +22,22 @@ def random_reservation_id():
     return random_id(prefix='r')
 
 
-def random_ami_id():
-    return random_id(prefix='ami')
-
-
 def random_security_group_id():
     return random_id(prefix='sg')
 
 
+def random_snapshot_id():
+    return random_id(prefix='snap')
+
+
+def random_spot_request_id():
+    return random_id(prefix='sir')
+
+
+def random_subnet_id():
+    return random_id(prefix='subnet')
+
+
 def random_volume_id():
     return random_id(prefix='vol')
 
@@ -34,14 +46,6 @@ def random_vpc_id():
     return random_id(prefix='vpc')
 
 
-def random_subnet_id():
-    return random_id(prefix='subnet')
-
-
-def random_snapshot_id():
-    return random_id(prefix='snap')
-
-
 def instance_ids_from_querystring(querystring_dict):
     instance_ids = []
     for key, value in querystring_dict.iteritems():
diff --git a/tests/test_ec2/test_spot_instances.py b/tests/test_ec2/test_spot_instances.py
index 0a08e243d..91a3158eb 100644
--- a/tests/test_ec2/test_spot_instances.py
+++ b/tests/test_ec2/test_spot_instances.py
@@ -1,9 +1,99 @@
+import datetime
+
 import boto
 import sure  # noqa
 
 from moto import mock_ec2
+from moto.core.utils import iso_8601_datetime
 
 
 @mock_ec2
-def test_spot_instances():
-    pass
+def test_request_spot_instances():
+    conn = boto.connect_ec2()
+
+    conn.create_security_group('group1', 'description')
+    conn.create_security_group('group2', 'description')
+
+    start = iso_8601_datetime(datetime.datetime(2013, 1, 1))
+    end = iso_8601_datetime(datetime.datetime(2013, 1, 2))
+
+    request = conn.request_spot_instances(
+        price=0.5, image_id='ami-abcd1234', count=1, type='one-time',
+        valid_from=start, valid_until=end, launch_group="the-group",
+        availability_zone_group='my-group', key_name="test",
+        security_groups=['group1', 'group2'], user_data="some test data",
+        instance_type='m1.small', placement='us-east-1c',
+        kernel_id="test-kernel", ramdisk_id="test-ramdisk",
+        monitoring_enabled=True, subnet_id="subnet123",
+    )
+
+    requests = conn.get_all_spot_instance_requests()
+    requests.should.have.length_of(1)
+    request = requests[0]
+
+    request.state.should.equal("open")
+    request.price.should.equal(0.5)
+    request.launch_specification.image_id.should.equal('ami-abcd1234')
+    request.type.should.equal('one-time')
+    request.valid_from.should.equal(start)
+    request.valid_until.should.equal(end)
+    request.launch_group.should.equal("the-group")
+    request.availability_zone_group.should.equal('my-group')
+    request.launch_specification.key_name.should.equal("test")
+    security_group_names = [group.name for group in request.launch_specification.groups]
+    set(security_group_names).should.equal(set(['group1', 'group2']))
+    request.launch_specification.instance_type.should.equal('m1.small')
+    request.launch_specification.placement.should.equal('us-east-1c')
+    request.launch_specification.kernel.should.equal("test-kernel")
+    request.launch_specification.ramdisk.should.equal("test-ramdisk")
+    request.launch_specification.subnet_id.should.equal("subnet123")
+
+
+@mock_ec2
+def test_request_spot_instances_default_arguments():
+    """
+    Test that moto set the correct default arguments
+    """
+    conn = boto.connect_ec2()
+
+    request = conn.request_spot_instances(
+        price=0.5, image_id='ami-abcd1234',
+    )
+
+    requests = conn.get_all_spot_instance_requests()
+    requests.should.have.length_of(1)
+    request = requests[0]
+
+    request.state.should.equal("open")
+    request.price.should.equal(0.5)
+    request.launch_specification.image_id.should.equal('ami-abcd1234')
+    request.type.should.equal('one-time')
+    request.valid_from.should.equal(None)
+    request.valid_until.should.equal(None)
+    request.launch_group.should.equal(None)
+    request.availability_zone_group.should.equal(None)
+    request.launch_specification.key_name.should.equal(None)
+    security_group_names = [group.name for group in request.launch_specification.groups]
+    security_group_names.should.equal(["default"])
+    request.launch_specification.instance_type.should.equal('m1.small')
+    request.launch_specification.placement.should.equal(None)
+    request.launch_specification.kernel.should.equal(None)
+    request.launch_specification.ramdisk.should.equal(None)
+    request.launch_specification.subnet_id.should.equal(None)
+
+
+@mock_ec2
+def test_cancel_spot_instance_request():
+    conn = boto.connect_ec2()
+
+    conn.request_spot_instances(
+        price=0.5, image_id='ami-abcd1234',
+    )
+
+    requests = conn.get_all_spot_instance_requests()
+    requests.should.have.length_of(1)
+
+    conn.cancel_spot_instance_requests([requests[0].id])
+
+    requests = conn.get_all_spot_instance_requests()
+    requests.should.have.length_of(0)