Two ways of realization of process of a counter-diffusion of reagents are considered. The one is the diffusion of reagents A and B in a sample Simultaneously from opposite sides. The second is the diffusion of reagent A in a sample that contains reagent B. They allow forming various spatial distributions of particles of a solid phase in materials. It is shown, that the modifying of materials with a technique of concomitant diffusion of reagents in a combination with heat treatment may be taken as an instrument for preparation of materials and structures with new functional, in particular electrophysical, properties. (C) 2002 Elsevier Science B.V. All rights reserved.