The rates of solvolysis of 4-morpholinecarbonyl chloride (MPC) have measured at 35.0 oC in water, D2O, CH3OD,and in aqueous binary mixtures of acetone, ethanol, methanol, and 2,2,2-trifluoroethanol. An extended (two-term)Grunwald-Winstein equation correlation gave sensitivities towards changes in solvent nucleophilicity and solvent ionizing power as expected for a dissociative SN2 and/or SN1(ionization) pathway. For nine solvents specific rates were determined at two additional temperatures and higher enthalpies and smaller negative entropies of activation were observed, consistent with the typical dissociative SN2 or SN1(ionization) pathway. The solvent deuterium isotope effect values for the hydrolysis of MPC of kH2O/kD2O = 1.27 and for the methanolysis of MPC of kMeOH/kMeOD = 1.22are typical magnitudes of the SN1 or ionization mechanism.