Friday's 54-pitch session was Halladay's second this week. He also threw in the bullpen Tuesday.
Halladay (10-1) is tied with Minnesota's Kevin Slowey for the major league lead in wins and has won seven straight decisions. His ERA of 2.53 is third lowest in the AL.
Halladay left a June 12 outing against Florida two pitches into the fourth inning due to a sore groin, the only time in 14 starts this season he has not gone at least seven. He felt discomfort after throwing again in Philadelphia last Wednesday and was placed on the disabled list retroactive to June 13.