Enabling the Root account is rarely necessary. Almost everything you need to do as administrator of an Ubuntu system can be done via sudo or gksudo. If you really need a persistent Root login, the best alternative is to simulate a Root login shell using the following command…

sudo -i

To enable the Root account (i.e. set a password) use:

sudo passwd root

Logging in to X as root may cause very serious trouble. If you believe you need a root account to perform a certain action, please consult the official support channels first, to make sure there is not a better alternative.

Re-disabling your root account

If for some reason you have enabled your root account and wish to disable it again, use the following command in terminal…

sudo passwd -dl root