Application of paraffin as a MW-transparent matrix for microwave pyrolysis of metalorganic compounds enables synthesis of large quantities of nanosized powders with excellent storability and packing behavior. Fully crystalline, nanosized t-ZrO2 powders with specific surface area > 200 m 2 g -1 are obtained from Zr-alcoholate, and alumina powders with > 500 m2g-1 from Al-alcoholates. Some differences exist between microwave pyrolysis and conventional pyrolysis of such mixtures. Powders from microwave pyrolysis transform at lower calcination temperature to α-A12O3 and exhibit after calcination a more homogeneous morphology as compared to powders from conventional pyrolysis. Furthermore, a different composition of the volatile pyrolysis products is found. t-ZrO2 powder from the microwave processing route exhibits an increased stability towards transformation to monoclinic ZrO2 as well as smaller initial grain sizes than a conventionally synthesized powder.