The most sensitive part of superconducting rotors for power stations is the optimal design of the liquid-helium region and long-term operation performance of the insulation system. The authors report on the thermal design of the entire rotor structure. Following a rough estimate of the heat losses using mean values for the material properties, some numerical results of calculation codes for the stationary temperature profiles are reported. Transient temperature profiles in individual parts of the rotor are given. The results are compared with experimental measurements of a test rotor.