Sure, it works like any other EF lens.
Although you won't have the special focus capability that STM lenses have when mounted on T4i and T5i (smooth tracking focus in video mode, even when it's not really usable on video yet..)
"STM functionality provides quiet, smooth and continuous autofocus during video operation (video continuous autofocus only when used with the Canon EOS Rebel T4i)"
On the 5D, the AF will work almost as on any other lens.
Cheers
