Cookie, I've used enameled casseroles in my grill many times and never have had a problem, knock on wood When I used them it was at the normal oven temps and the most that ever happened was that they require a little more cleaning if smoke collected on the outside. I wouldn't want to say what might happen if you used a very high temp. but I never had reason to do that. I was just cooking a casserole the same as I would in the kitchen oven.