PURPOSE: To easily obtain a perfect metal oxide by dehydrating an aq. soln. contg. a water soluble metal complex compd. and a specified sublimable compd. by heating and by further heating the resulting powder in the air.

CONSTITUTION: An aq. soln. contg. one or more kinds of water soluble metal complex compds. and a compd. sublimable at a temp. below the thermal decomposition temps. of the complex compds. is dehydrated by heating and the resulting powder is further heated in an oxidizing atmosphere. Complex compds. of ammonia are especially effective as the metal complex compds, An ammonium compd. leaving no residue of a decomposed product after sublimation, e.g., ammonium chloride is especially suitable for use as the sublimable compd.