Abstract: An improved process is provided for the preparation of siloxane-oxyalkylene copolymers by a solventless process via hydrosilation of oxyethylene-rich polyethers in the presence of carboxylic acids or carboxylic acid salts as a catalyst modifier. The use of a carboxylic acid or salt prevents acetal formation through the hydroxyl groups of the polyether and/or copolymer. The use of solvent, acetal treatment and solvent stripping steps of the conventional processes are eliminated and accordingly, environmental as well as economic benefits are achieved.