The specific rates of solvolysis of neopentyl fluoroformate (NeopOCOF, 1) have been measured at 45.0 oC in pure and binary solvent mixtures. These results correlated well with the extended Grunwald-Winstein equation in all of the solvents except the four TFE-ethanol binary solvents. Leaving group effects (kF/kCl values) and sensitivity (l and m values) to changes in solvent nucleophilicity and solvent ionizing power are appreciably similar to those observed previously for the solvolyses of primary and secondary alky haloformates. This is consistent with the addition-elimination pathway as rate-determining. The kinetic solvent isotope effects (KSIEs, kMeOH/kMeOD) and activation parameters for the solvolyses of 1 were also determined. The results are compared with those reported earlier for neopentyl chloroformate (NeopOCOCl, 2) and other alkyl haloroformate esters.