CHF experiments in tubes and annulus cooled with HFC-134a have been performed. The HFC-134a and water CHF data have been compared by applying the Ahmad and the Katto modeling parameters. For the mass fluxes from 7 10 to 3500 kg m(-2) s(-1) in the tubes, the HFC-134a and water CHF data fall close to the same curve on the plane of the dimensionless CHF vs. the Ahmad and the Katto modeling parameters. For the mass fluxes below 600 kg m(-2) s(-1) in an annulus, the dimensionless CHFs as a function of the Ahmad and the Katto modeling parameters show a large difference between the HFC-134a and the water. The Katto and the Ahmad modeling parameters cannot be correlated with the dimensionless CHF data for HFC-134a and water on the same curve in the low mass flux and high quality conditions. (C) 2005 Elsevier Ltd. All rights reserved.