Hi, You first have to build a 64bit Qt with MinGW. This wiki article might help you get started. Hope it helps

yes, specify 32 and 64 for msvc2015 i was able to ignore the warnings the kits i picked worked

@yigene To add to @mrjj : does your app need that amount of memory? If not and it does not have memory leaks than there is no real reason to have it as 64bit.