PURPOSE: To produce the title fine powder contg. scarcely agglomerated particles by heating crystalline hydrous zirconyl chloride or a solid mixture consisting primarily thereof at a specified temp. in a closed vessel, holding the product at the temp., then heating, dehydrating, caking, drying or calcining after releasing the product from tightly closed condition.

CONSTITUTION: Crystalline hydrous zirconyl chloride alone, or a solid mixture consisting primarily of the crystalline hydrous zirconyl chloride contg. also ≤0.2 (by molar ratio basing on Zr) one kind of metal salt or metal hydroxide which can be dissolved in ZrO2 as solid soln. and forming metal oxide, is used. The material is heated at 150W300°C in a closed vessel, and held for a sufficient time necessary for generating crystallized ZrO2. In this stage, said zirconyl chloride is hydrolyzed slowly by its own water of crystallization to form white paste mixture. Then, the vessel is released from tightly closed condition, and the product is dehydrated by heating as it is, and dried or calcined. By this method, relatively coarse fine particles having ≥0.3μ particle size of relatively uniform particle size distribution are obtd.