Procaine solutions are subject to hydrolytic deteriortion. In the present paper results of a chemical kinetical investigation of this reaction together with its theoretical analysis are given. It is shown that the over-all reaction is the sum of two reactions involving the free base and the singly charged ion. The activation energies have been found to be 13.8 and 12 kilocalories per mole, respectively, for the two hydrolytic reactions. From the data obtained general equations relating the half life of procaine solutions to their temperature and pH are derived.