diff --git a/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java b/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java
index 2d917bb..a6b0701 100644
--- a/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java
+++ b/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java
@@ -43,6 +43,7 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 
+import org.onlab.util.HexString;
 import static org.onlab.util.Tools.nullIsNotFound;
 
 /**
@@ -110,7 +111,12 @@
     public Response getGroupByDeviceIdAndAppCookie(@PathParam("deviceId") String deviceId,
                                                    @PathParam("appCookie") String appCookie) {
         final DeviceId deviceIdInstance = DeviceId.deviceId(deviceId);
-        final GroupKey appCookieInstance = new DefaultGroupKey(appCookie.getBytes());
+
+        if (!appCookie.startsWith("0x")) {
+            throw new IllegalArgumentException("APP_COOKIE must be a hex string starts with 0x");
+        }
+        final GroupKey appCookieInstance = new DefaultGroupKey(HexString.fromHexString(
+                appCookie.split("0x")[1], ""));
 
         Group group = nullIsNotFound(groupService.getGroup(deviceIdInstance, appCookieInstance),
                 GROUP_NOT_FOUND);
@@ -172,7 +178,12 @@
     public void deleteGroupByDeviceIdAndAppCookie(@PathParam("deviceId") String deviceId,
                                                   @PathParam("appCookie") String appCookie) {
         DeviceId deviceIdInstance = DeviceId.deviceId(deviceId);
-        GroupKey appCookieInstance = new DefaultGroupKey(appCookie.getBytes());
+
+        if (!appCookie.startsWith("0x")) {
+            throw new IllegalArgumentException("APP_COOKIE must be a hex string starts with 0x");
+        }
+        GroupKey appCookieInstance = new DefaultGroupKey(HexString.fromHexString(
+                appCookie.split("0x")[1], ""));
 
         groupService.removeGroup(deviceIdInstance, appCookieInstance, null);
     }
diff --git a/web/api/src/main/resources/definitions/Groups.json b/web/api/src/main/resources/definitions/Groups.json
index e2be807..04273e0 100644
--- a/web/api/src/main/resources/definitions/Groups.json
+++ b/web/api/src/main/resources/definitions/Groups.json
@@ -67,6 +67,11 @@
             "description": "types of the group",
             "example": "ALL"
           },
+          "deviceId": {
+            "type": "string",
+            "description": "device identifier",
+            "example": "of:0000000000000003"
+          },
           "appId": {
             "type": "string",
             "description": "application identifier",
diff --git a/web/api/src/main/resources/definitions/GroupsPost.json b/web/api/src/main/resources/definitions/GroupsPost.json
index 7ea7b50..203e2e4 100644
--- a/web/api/src/main/resources/definitions/GroupsPost.json
+++ b/web/api/src/main/resources/definitions/GroupsPost.json
@@ -3,7 +3,6 @@
   "title": "group",
   "required": [
     "type",
-    "deviceId",
     "appCookie",
     "groupId",
     "buckets"
@@ -13,10 +12,6 @@
       "type": "string",
       "example": "ALL"
     },
-    "deviceId": {
-      "type": "string",
-      "example": "of:0000000000000001"
-    },
     "appCookie": {
       "type": "string",
       "description": "application cookie. Arbitrary length byte array represented in hex string",
@@ -82,4 +77,4 @@
       }
     }
   }
-}
\ No newline at end of file
+}
diff --git a/web/api/src/test/java/org/onosproject/rest/GroupsResourceTest.java b/web/api/src/test/java/org/onosproject/rest/GroupsResourceTest.java
index 4d4c933..680a371 100644
--- a/web/api/src/test/java/org/onosproject/rest/GroupsResourceTest.java
+++ b/web/api/src/test/java/org/onosproject/rest/GroupsResourceTest.java
@@ -94,14 +94,14 @@
     final Device device2 = new DefaultDevice(null, deviceId2, Device.Type.OTHER,
             "", "", "", "", null);
 
-    final MockGroup group1 = new MockGroup(deviceId1, 1, "111", 1);
-    final MockGroup group2 = new MockGroup(deviceId1, 2, "222", 2);
+    final MockGroup group1 = new MockGroup(deviceId1, 1, "0x111", 1);
+    final MockGroup group2 = new MockGroup(deviceId1, 2, "0x222", 2);
 
-    final MockGroup group3 = new MockGroup(deviceId2, 3, "333", 3);
-    final MockGroup group4 = new MockGroup(deviceId2, 4, "444", 4);
+    final MockGroup group3 = new MockGroup(deviceId2, 3, "0x333", 3);
+    final MockGroup group4 = new MockGroup(deviceId2, 4, "0x444", 4);
 
-    final MockGroup group5 = new MockGroup(deviceId3, 5, "555", 5);
-    final MockGroup group6 = new MockGroup(deviceId3, 6, "666", 6);
+    final MockGroup group5 = new MockGroup(deviceId3, 5, "0x555", 5);
+    final MockGroup group6 = new MockGroup(deviceId3, 6, "0x666", 6);
 
     public GroupsResourceTest() {
         super(CoreWebApplication.class);
@@ -460,7 +460,7 @@
                 .andReturn(group5).anyTimes();
         replay(mockGroupService);
         final WebResource rs = resource();
-        final String response = rs.path("groups/" + deviceId3 + "/" + "111").get(String.class);
+        final String response = rs.path("groups/" + deviceId3 + "/" + "0x111").get(String.class);
         final JsonObject result = Json.parse(response).asObject();
         assertThat(result, notNullValue());
 
@@ -481,7 +481,7 @@
                 .andReturn(null).anyTimes();
         replay(mockGroupService);
         final WebResource rs = resource();
-        final ClientResponse response = rs.path("groups/" + deviceId3 + "/" + "222").get(ClientResponse.class);
+        final ClientResponse response = rs.path("groups/" + deviceId3 + "/" + "0x222").get(ClientResponse.class);
 
         assertEquals(404, response.getStatus());
     }
@@ -517,7 +517,7 @@
 
         WebResource rs = resource();
 
-        String location = "/groups/1/111";
+        String location = "/groups/1/0x111";
 
         ClientResponse deleteResponse = rs.path(location)
                 .type(MediaType.APPLICATION_JSON_TYPE)