Abstract: A process for the fractional production of alkyltin oxides which comprises the steps of:subjecting a mono-, di- or trialkyltin halide to continuous hydrolysis at a temperature between 30.degree. to 100.degree. C. for a period of 10 minutes to 3 hours by the use of a 1% to 50% aqueous solution of a basic substance, thereby forming in the hydrolysis reaction mixture a dialkyltin oxide having an average particle diameter of 10 .mu.m or more, provided that where an intended alkyltin oxide is solid, the continuous hydrolysis is performed in the presence of an organic solvent slightly soluble in water and having a boiling point as measured under ordinary pressure of 150.degree. C. or lower and a specific gravity of 1.1 or smaller;allowing the resulting reaction mixture to stand, thereby to form three phases composed of an organic phase, an aqueous phase, and a phase consisting substantially of the dialkyltin oxide and having a specific gravity 0.