1. From the Apple Menu, open "System Preferences..."
  2. In the "Internet & Wireless" (Internet & Network in older versions) section, select the "Network control panel"
  3. Select the desired network device in the list. This will typically be "Ethernet" for the wired Ethernet port or "AirPort" for the wireless network
  4. Click the "Advanced..." button in the lower right corner
  5. Select the "Ethernet"
  6. The value listed beside Ethernet ID: or AirPort ID: is the Hardware MAC Address for the selected network device. It will be in the format: XX:XX:XX:XX:XX:XX