Isothermal (vapour + liquid) equilibrium data were measured for the (1,1,1-trifluoroethane (HFC-143a) + isobutene) as an alternative refrigerant in the temperature range from (273.15 to 348.15) K at 15 K intervals. A circulating-type apparatus with on-line gas chromatography was used in these experiments. The experimental data were correlated well by Peng-Robinson equation of state using the Wong-Sandler mixing rules. (C) 2008 Elsevier Ltd. All rights reserved.