diff --git a/moto/ec2/models.py b/moto/ec2/models.py
index 574621001..166858960 100644
--- a/moto/ec2/models.py
+++ b/moto/ec2/models.py
@@ -299,7 +299,7 @@ class Instance(BotoInstance, TaggedEC2Resource):
         self.subnet_id = kwargs.get("subnet_id")
         self.key_name = kwargs.get("key_name")
         self.source_dest_check = "true"
-        self.launch_time = datetime.now().strftime('%y-%m-%dT%H:%M:%S%z')
+        self.launch_time = datetime.now().isoformat()
 
         self.block_device_mapping = BlockDeviceMapping()
         self.block_device_mapping['/dev/sda1'] = BlockDeviceType(volume_id=random_volume_id())