The effects of temperature and microwave frequency on the dielectric properties of MoS2 and Pt catalysts together with an aluminum oxide support were investigated. Dielectric constants and dielectric loss factors were measured in a temperature range of 200-800degreesC by a cavity resonator technique with a cylindrical copper cavity resonating in TM0n0 modes (n = 1, 2,...,5), which corresponded to frequencies of 0.615, 1.413, 2.216, 3.020, and 3.825 GHz.