The specific rates of solvolysis of methyl fluoroformate have been measured at $40.0;{^{circ}C}$ in several hydroxylic solvents. Analysis with the extended Grunwald-Winstein equation leads to sensitivities toward changes in solvent nucleophilicity (l) of $1.33;{pm};0.10$ and toward changes in solvent ionizing power (m) $0.73;{pm};0.06$. For methanolysis, a solvent deuterium isotope effect of 3.98 is compatible with the incorporation of general-base catalysis into the substitution process. For four representative solvents, studies were made at several temperatures and activation parameters determined. These observations are also compared with those previously reported for alkyl halogenoformate esters and mechanistic conclusions are drawn.