The MAC Address of your Hue Bridge can be found on the back of the Bridge on a label with a bar code.The MAC Address of your Hue Bridge 2.0 can be found in the red box of the image below.
It will be a total of 6 numbers/characters however this is not the complete MAC Address. You have to add 00:17:88 followed by what is on the back of your bridge. For instance, if your bridge shows 1a2b3c then your complete MAC address would be 00:17:88:1a:2b:3c.
The complete MAC address can be found in the red box of the image below on the Hue Bridge 1.0