The temperature of the high temperature superconducting (HTSC) sample surface, T, irradiated by the c.w. IR CO-laser was measured by the pyrometric method. The YBa2Cu3O7 single crystals, YBa2Cu3O6.2, YBa2Cu3O6.9, and the Nd1.85Ce0.15CuO4 ceramic samples were studied. The experimental data were compared with the theoretical estimations. The verified values of the heat conductivity, k, were derived from this comparison. Using these k values, the T data for the case of the pulse laser irradiation obtained in our previous investigations of laser irradiation effects were refined. The results of the present work confirmed that effects of the IR laser irradiation seen in our previous works cannot be explained by pure thermal action as the degree of the IR laser thermal effects, i.e., the heating, is relatively small in that experiments, and the T values are lower than it is needed for appreciable changes in properties of the HTSC samples being under consideration.