Zirconia and yttria stabilized zirconia (3YSZ) nanoparticles were prepared from zirconia and yttria salts using molten salts (MS) and microwave (MW) synthesis. The crystalline ZrO2 and 3YSZ nanoparticles with crystallite size in the range of 3-27 nm were obtained by MS synthesis in NaCl-NaNO3 salts. The zirconia and 3YSZ powders with close characteristics were obtained by combining MW synthesis with calcination of products at 400-800 °C. The crystallite size depends upon synthesis or calcination temperature, and the precursors used. The powders prepared by MS and MW synthesis ensured manufacturing of bulk materials with relative density of 98.6% and 97.2% respectively by using spark plasma sintering at 1300 °C. © Published under licence by IOP Publishing Ltd.