By default, OS X doesn’t setup a password for your root login. There are few occasions you may want to access terminal as Super User (su), this will ask for your root password.

It’s very simple to setup root password as long as you have Admin Access (First user created on installation OS X will be Admin level user).

• First you will have to logged in as Admin level user
• Open your Terminal (Located Applications/Utilities/Terminal)
• Type in command: sudo passwd root

This command will ask for your su password, at this time it’s only asking you’re admin level user passwords.

Once you entered, terminal will ask for new password for root user twice to verify and update. Remember, if you loose your root password, it’s May not be possible to recover it…

There are other methods for becoming root user or changing root user password. For a full list visit: http://www.spy-hill.com/~myers/help/apple/EnableRoot.html