Direct grilling of boneless chicken thighs should take 15 to 20 minutes and grilling indirectly with the grill chamber temperature at 350 degrees should take 35 to 45 minutes. The time varies in accordance to the thickness of the chicken.irst, I would recommend that you cook them in a covered dish as chicken breasts tend to get a little dry. You might want to put little water or broth in the bottom of the dis … h, as well. Cook at 350degrees for about 40-45 minutes.