Kinetic data on the hydration of ethylene oxide was obtained from both uncatalyzed and heterogeneously catalyzed reactions using a pressurized batch reactor. Amberjet 4200/HCO3- was used as the heterogeneous catalyst, which was found to be the most effective among the four types of cross-linked styrene-divinylbenzene anion-exchange resins tested. The reactions were proved to follow a series-parallel irreversible homogeneous mechanism under both catalyzed and uncatalyzed conditions. Thus the corresponding rate expression can be given as -r(EtO) = k(1)C(W)C(EtO) + k(2)C(MEG)C(EtO) + k(3)C(DEG)C(EtO). The rate constants were determined by applying the method of averages at different temperatures. The temperature dependency of the rate constants was found to be k(1)/[L/(mol.min)] = exp(13.62 - 8220/T), k(2)/[L/(mol.min)] = exp(15.57 - 8700/T), and k(3)/[L/(mol.min)] = exp(16.06 - 8900/T) for the uncatalyzcd reactions and k(1)[L/(mol.min)] = exp(19.60 - 9580/T), k(2)/[L/ (mol.min)] = exp(20.19 - 10171/T), and k(3)/[L/(mol.min)] = exp(19.06 - 9743/T) in the presence of catalyst of 0.15 mol of HCO3-/L in equivalent, where T is the absolute temperature in kelvin.