An investigation is made of the boiling of liquids (water, petroleum) in a powerful microwave beam for converting the microwave power into mechanical work (microwave steam engine), for self-pumping, for fractionation of liquids (separation of volatile fractions, rectification, desalination), for accelerating diffusion, for facilitating fluid penetration through porous media, etc. The possibility is noted of cracking fuel in a microwave discharge or microwave heating.