PURPOSE: To deoxidize a chlorinated hydrocarbon solvent, e.g. a used cleaning agent, while maintaining the residual retention of various additives at a high value, by bringing the surface of the solvent to be deoxidized into contact with an alkaline aqueous solution, and allowing both to stand for a necessary time.
CONSTITUTION: A chlorinated hydrocarbon solvent containing a variety of stabilizers, e.g. an antioxidant, condensation reaction inhibitor or acid capturing agent, used as a cleaning agent is deoxidized for regeneration by adding a suitable amount of an alkaline aqueous solution to the surface of the solvent in a layer, allowed to stand and neutralized. Preferably, an aqueous solution of an alkaline earth metallic hydroxide in a concentration of 1/7,000W1/400N as an alkali metal in a quantity of about 5W15vol% based on the solvent to be treated as the alkaline aqueous solution is brought into contact with the solvent, or aqueous ammonia or alkali metallic hydroxide is brought into contact with the solvent.