I do this quite often, in fact this evening's supper will include chicken breasts previously bagged, cooked Sous Vide, then frozen. To reheat, I set the Sous Vide Supreme to one degree lower than the cooking temperature then when it reaches that temperature I put the still frozen chicken breasts, still in their vac bags, in the SVSupreme for about 40 minutes. As the food has been previously cooked it will be safe, and as the temp is just fractionally lower than the cooking temp it doesn't matter at all if you leave it in the water for quite a bit longer. At first I was really surprised that the relatively low temp would not only defrost but bring it up to eating temp in such a short time.