I haven't tested them against boiling water or steam because quite frankly, I would imagine that dipping my hand in boiling water would probably not be a good idea. I have had 3rd degree burns on my hands from a boiling water incident years ago, and don't want to go through that pain again, so I will not be testing that (at least not intentionally) with these gloves. I would advise against it though, just to be on the safe side.
They do work well for the intended purpose of removing hot pots and pans, or grabbing hot dishes out of the microwave. They also work well for opening stubborn jars because of the silicone gripper strips, and changing light bulbs is no longer a problem. I will be testing them next summer for grilling, although I see no reason why they wouldn't work great. Just don't expose them to the open flames and you should be fine.
Although I got this product at a discount or received a complimentary sample in exchange for my honest review, all thoughts and opinions on the products I review are always my own and have not been influenced by any discounts or samples which may have been provided to me.