A diagram of the CuInSe2-In2Te3 system state is constructed using the methods of physicochemical analysis. The system is quasi-binary with limited areas of solid solutions based on both source components. The investigations of thermal conductivity of the (CuInSe2)(0.99)(In2Te3)(0.01) solid solution demonstrate a complex nature of the heat transfer attributed to both a multicomponent structure of the composition and a defect crystalline structure.