The rates of solvolysis of 4-morpholinecarbonyl chloride (MPC) have measured at $35.0^{circ}C$ in water, $D_2O$, $CH_3OD$, 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 $S_N2$ and/or $S_N1$(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 $S_N2$ or $S_N1$(ionization) pathway. The solvent deuterium isotope effect values for the hydrolysis of MPC of $k_{H_2O}/k_{D_2O}$ = 1.27 and for the methanolysis of MPC of $k_{MeOH}/k_{MeOD}$ = 1.22 are typical magnitudes of the $S_N1$ or ionization mechanism.