It is necessary to know for calculation of solid household wastes thermal processing thermophysical characteristics. Existing methods consider the solid household waste layer as a multicomponent mix which thermophysical characteristics are defined taking into account volume fractions and properties of components, layer porosity thus not. A technique is proposed for determining the effective coefficient of thermal diffusivity of a multicomponent porous layer, constructed on the basis of the solution of the inverse heat conduction problem. The base of problem-solving procedure is the method of the discrete satisfaction of boundary conditions (DSBC). According to the proposed method, the dependence of the effective coefficient of thermal diffusivity of solid communal waste of the average morphological composition on the temperature and porosity of the layer was determined. The proposed technique can be used to determine the effective coefficient of thermal diffusivity of bodies with different porosity structures.