The thermochemical properties (Delta H-298(0), S-298(0), H-298(0)-H-0(0), C-p(T), T and Delta H phase transformation) for YBa2Cu3O6, YBa2Cu3O7, YBa2CU3.5O7.5, YBa2Cu4O8, YBa2Cu5O9, YBa4CU3O8.5, Y2BaCuO5, YCuO2, Y2Cu2O5, Y2BaO4, Y2Ba2O5, Y2Ba4O7, Y4Ba3O9, BaCuO2, BaCu2O2, Ba2CuO3 and Ba3CU5O8 are presented, For every complex oxide, the numerical coefficient of the polynomial approximation of the reduced Gibbs energy temperature dependence is calculated.