Let us consider the combustion of a liquid propellant film moving under the action of gravity along a plane vertical plate. At a certain distance from the free surface a diffusion plume is formed on whose front the burnup of liquid vapors occurs in a gaseous oxidizer (Fig. la). Fluid evaporation during its running off results in grar thinning of the film and specifies the finiteness of its length. Viscosity and evaporation phenomena form longitudinal and transverse inhomogenelties in the liquid layer and occur in the gas phase under the effect of a chemical transformation of the substance stimulating intensive heat and mass transfer,