This invention relates to a process for the reduction of color of polymethylene poly(phenylisocyanates). This process comprises mixing a polymethylene poly(phenylisocyanate) with an epoxide having an epoxide equivalent weight of about 44 to about 700, and heating this mixture to a temperature of from about 35 to about 150.degree. C. for at least about 15 minutes, with stirring. Suitable epoxides include epoxidized fatty acid monoglycerides, epoxidized fatty acid diglycerides, epoxidized fatty acid triglycerides, epoxidized dimer fatty acids and epoxidized trimer fatty acids.