[kathrynmaksym]

What happens if iron is placed in hot water?

[RickJ]

I'm no chemist, but I think nothing, really... except that the iron would get warm.

... and eventually the iron would rust.

Are you looking for - or thinking there is - a more substantial reaction between iron and water?

Now, if you mean an iron as what we iron clothes with, you could get electrocuted if it's plugged in!