Good luck with that, been trying to find a way myself. They say anti-perspirant powder will help keep cool but I have yet to try it. Luckily I work in a machine shop where we have air hoses everywhere. I'll shove an air wand down the side of my boot and blast air in when they get too hot. They make vented biker boots, but wouldn't work for me as I have to have steel toe and preferably water proof.