Polysiloxane hydrolyzates are neutralized by treating polysiloxane hydrolyzates containing residual acidic constituents with carbon, and then the carbon is removed from the treated neutralized polysiloxane hydrolyzate. Some examples of polysiloxane hydrolyzates that can be treated are hydride functional polysiloxane hydrolyzates and polydiethylsiloxane hydrolyzates. The carbon neutralizing agent especially preferred is carbon derived from bituminous coal. The carbon is removed from the treated neutralized polysiloxane hydrolyzate by passing it through solid liquid separation devices such as plate and frame filter presses, polishing filters, and post filters for removing fines.