We had earlier seen the steps required for finding saved WiFi password on Windows 7 system. Similarly you can recover the WiFi password on Mac OS X Lion using Keychain Access utility.
Step 1: Launch Keychain Access utility through Spotlight search.
Step 2: In the Keychain Access window, select Passwords under Category
Step 3: Now select login under Keychain and double click on the name of the WiFi network for which you want to recover password.
Step 4: This would display the folllowing WiFi network login password window.
Step 5: Mark the check box with label as Show password, which would ask you to enter the Mac password.
After validating the entry, the WiFi network password will be displayed next to Show password. By this way you can recover WiFi password on a Mac system.