Rate constants for the reactions of OH with HFC-134a (CF3CH2F) have been measured relative to CH3CCl3, CH4, and HFC-125 (CF3CHF2). Rate constants for HFC-134 (CF2HCF2H) were measured relative to CH3CCl3, HFC-125, and HFC-134a. The measurements were made in a slow-flow, temperature controlled photochemical reactor, were based on relative rates of disappearance of the parent compounds as measured by FTIR spectroscopy. The temperature range was 298--358 K. Hydroxyl radicals were generated by 254 nm photolysis of O3 in the presence of water vapor. Using current NASA/JPL rate constants for the reference compounds, temperature dependent rate constants of both compounds were derived. Rate constants obtained from the different reference compounds are in excellent agreement. The presently recommended rate constant for HFC-134a [JPL 92-20, 1992; IUPAC, 1992> is too high by about 25%. ¿ American Geophysical Union 1993