The heat capacity C-p, thermal diffusivity (T), and lattice thermal conductivity (latt) of ceramic solid solutions of sesquisulfides Gd3-xVGd,xS4 (0 < x < 0.33) in the temperature range 300-700 K has been studied. Changing the real structure, namely the concentrations of vacancies (N-V) and deformation (N-Dc) centers of polycrystals, significantly decreases (latt). A deviation of composition from the stoichiometry 2:3 is accompanied by an increase in the specific area of the crystallite boundaries per unit volume, and, hence, the concentration of deformation centers D-C increases. This observation was confirmed by examining the short-range order disturbance of the lattice and symmetry environment of the Gd3+ and S2- environment by Raman spectroscopy and the magnetic susceptibility Faraday method. Therefore the thermal diffusivity of gadolinium sesquisulfide is reduced because of the mean free path of phonons decrease. As a result, the thermal conductivity of the polycrystalline samples is reduced by 10%.