Process for the preparation of diorganotin-dicarboxylates

The invention relates to a process for the preparation of a pulverulent diorganotin dicarboxylate, characterised in that a diorganotin oxide of the formula I in which R and R , independently of one another, are C1-C18-alkyl, is reacted with a dicarboxylic acid of formula II in which R is C1-C18-alkylene, cycloalkylene having 5 to 7 carbon atoms, phenylene, C1-C18-alkenylene or C1-C8-alkylene which is substituted by 1 or 2 hydroxyl groups, or the anhydride thereof, at a temperature in the range of 45 DEG C to 70 DEG C in the absence of solvents and adsorbents, and the reaction mixture and product are constantly mixed during the reaction and the subsequent cooling phase. The resultant diorganotin dicarboxylates are suitable for the stabilisation of chlorine-containing polymers against the harmful effects of light, oxygen and/or heat.