Starting materials for tungsten production (APT, AMT, WO 3·H 2O, and stoichiometric and substoichiometric dehydrated deammoniated powders) have been treated with microwave power. The increase in temperature has been registered. Time-temperature plots have been recorded. The temperature slopes in the room-temperature range have been compared with room-temperature dielectric-loss data at microwave frequencies. Some perspectives of microwave powder processing and test methods based on the varying microwave-transparency (dielectric-loss factor) of the materials involved are shown. The microwave calcination of APT is demonstrated. Dehydration process can easily be followed.