Isothermal vapor-liquid equilibrium data for the binary mixture of 2,3,3,3-tetrafluoroprop-1-ene (HFO-1234yf) + isobutane (HC-600a) were measured at temperatures from 283.15 to 323.15K using a recirculation apparatus. The experimental data were correlated using the Peng-Robinson equation of state with vdW mixing rule and Wong-Sandler mixing rule, respectively. The comparison between the correlation results and experimental data showed a good agreement, and Wong-Sandler mixing rule gave more accurate calculations for this binary system. Azeotropic behavior was found at high mole fraction of HFO-1234yf. (C) 2013 Elsevier B.V. All rights reserved.