Abstract: A ski boot comprising an external shell and a rigid sole, a slipper producing at least one cavity between the shell and the foot. The method of adjustment consists in filling the cavity with a moldable mixture of products kept in a viscous or paste-like state by means of at least one volatile product, and then eliminating at least one of the volatile products by causing it to pass into a gaseous phase until the mixture of products hardens. The invention has the particular advantage of making it possible to adjust the ski boot to a skier's foot without risk of compressing it in a dangerous manner.