The present invention relates to a process for dehydrochlorinating polyvinylchloride polymers to remove about 30 wt % chlorine therefrom by heating the starting materials PVC and deoxygenated liquid water, preferably neutral liquid water at temperatures from about 200.degree. C. up to the critical temperature of water at autogenous pressure to maintain the water as a liquid phase. The process has utility in recycling by enabling PVC to be dechlorinated specifically by a means that does not release chlorine gas.