Processes of diffusion and silicide formation in stressed multilayers of Mo/Si, as a result of their isothermal annealing, were studied in this paper by methods of cross-sectional transmission electron microscopy and X-ray diffraction techniques. It was found that reaction with growth of molybdenum disilicide of reduced density takes place at Mo-on-MoSi2 interfaces up to formation of similar to 7 mn thick layers, due to annealing treatment within 350-400 degrees C temperature range. Silicon atoms were found to be the dominating diffusive components. As a result of Si atoms' diffusion from Si layer, sublayers of a somewhat lower density are being formed at MoSi2-on-Si interfaces. Growth of molybdenum disilicide is accompanied by reduction of multilayer period. Activation energy of diffusion process (phase formation) makes up similar to 2.2 eV. Influence of compressive stresses (that exist in Mo layers) on process of phase formation, both in as-deposited and in annealed samples, is discussed in this paper. (C) 2007 Elsevier B.V. All fights reserved.