Some effects are analyzed which are related to the influence of electromagnetic radiation on transfer processes in heterogeneous systems. The influence exerted by the excitation of internal degrees of freedom of molecules in a field of the resonance laser radiation is considered, as well as the effect of volumetric heating of a porous catalyst particle in the field of microwave radiation. It is shown that on exposure to microwave radiation heterogeneous reaction in a particle of the porous catalyst can occur more uniformly over the particle volume. An expression is found for temperature distribution in a spherical particle of the porous catalyst resulting in a uniform course of chemical reaction over the particle volume. (C) 2001 Elsevier Science Ltd. Ali rights reserved.