The Avengers hunk briefly dated Kelly in 2007, and they were alleged to have reunited in August (12) following a cosy dinner date in Boston, Massachusetts.
And it appears the relationship is going strong - the stars were caught on camera locking lips on Monday (01Oct12) before stopping for lunch in Studio City.
The loved-up pair were snapped together again hours later as they drove away from Craig's restaurant after dinner, with Kelly trying her best to hide her face from the paparazzi.
Kelly previously dated baseball ace Derek Jeter. The couple split in 2011 after three years together.