A desensitizing solution and process For using the solution are disclosed to desensitize a diazo photosensitive printing plate after development. The solution comprises a water soluble desensitizing agent having the formula (FORMULA) where Y is an acid group or a water soluble salt of said acid group and wherein R is another Y, hydrogen, an aliphatic hydrocarbon or an aromatic hydrocarbon which reacts with any residual photosensitive diazo on the developed plate to render the diazo incapable of forming an oleophilic substance and a filming agent selected from water soluble aliphatic polyols have less than eight carbon units, the acid derived monoesters of these polyols, and the alkali metal salts of the monoesters.