Funnily enough I was thinking about cooking brown rice just the other day as I always seem to be using white rice, which is lovely, but I am missing the brown. My guess is that you cook it for the same length of time as you would if you were cooking it on the stove top - would that be right? I must do some research. Either my Rainbow Recipes or Vegetarian books should have an answer - I'm just not near enough to them at the moment to check.