diff --git a/moto/ssm/models.py b/moto/ssm/models.py
index c15a2047a..0f75599c3 100644
--- a/moto/ssm/models.py
+++ b/moto/ssm/models.py
@@ -150,19 +150,15 @@ class SimpleSystemManagerBackend(BaseBackend):
                 'DocumentName': kwargs['DocumentName'],
                 'Comment': kwargs.get('Comment'),
                 'ExpiresAfter': expires_after.isoformat(),
-                'Parameters': {
-                    'string': [
-                        'string',
-                    ]
-                },
+                'Parameters': kwargs['Parameters'],
                 'InstanceIds': kwargs['InstanceIds'],
                 'Targets': kwargs.get('targets'),
                 'RequestedDateTime': now.isoformat(),
                 'Status': 'Success',
                 'StatusDetails': 'string',
-                'OutputS3Region': 'string',
-                'OutputS3BucketName': 'string',
-                'OutputS3KeyPrefix': 'string',
+                'OutputS3Region': kwargs.get('OutputS3Region'),
+                'OutputS3BucketName': kwargs.get('OutputS3BucketName'),
+                'OutputS3KeyPrefix': kwargs.get('OutputS3KeyPrefix'),
                 'MaxConcurrency': 'string',
                 'MaxErrors': 'string',
                 'TargetCount': len(instances),
diff --git a/tests/test_ssm/test_ssm_boto3.py b/tests/test_ssm/test_ssm_boto3.py
index c9be673ac..5d6588732 100644
--- a/tests/test_ssm/test_ssm_boto3.py
+++ b/tests/test_ssm/test_ssm_boto3.py
@@ -463,15 +463,27 @@ def test_add_remove_list_tags_for_resource():
 @mock_ssm
 def test_send_command():
     ssm_document = 'AWS-RunShellScript'
-    script = '#!/bin/bash\necho \'hello world\''
+    params = {'commands': ['#!/bin/bash\necho \'hello world\'']}
 
     client = boto3.client('ssm', region_name='us-east-1')
+    before = datetime.datetime.now()
     response = client.send_command(
         InstanceIds=['i-123456'],
         DocumentName=ssm_document,
         TimeoutSeconds=60,
-        Parameters={'commands': [script]},
-        OutputS3BucketName='the-bucket'
+        Parameters=params,
+        OutputS3Region='us-east-2',
+        OutputS3BucketName='the-bucket',
+        OutputS3KeyPrefix='pref'
     )
+    cmd = response['Command']
 
-    assert response['Command']
+    cmd['CommandId'].should_not.be(None)
+    cmd['DocumentName'].should.equal(ssm_document)
+    cmd['Parameters'].should.equal(params)
+
+    cmd['OutputS3Region'].should.equal('us-east-2')
+    cmd['OutputS3BucketName'].should.equal('the-bucket')
+    cmd['OutputS3KeyPrefix'].should.equal('pref')
+
+    cmd['ExpiresAfter'].should.be.greater_than(before)