The isothermal VLE values for the system of {1,1,2,2-Tetrafluoroethane (R134) + trans-1,3,3,3-tetrafluoropropene (R1234ze (E))} at four temperatures from (258.150 to 288.150) K were measured in this work with an apparatus based on the static-analytic method. The correlation of VLE results was carried out by means of the Peng-Robinson equation of state and the Huron-Vidal mixing rules involving the NRTL activity coefficient model. Good consistency is found between the experimental and calculated values by this model at each experimental point. The average absolute relative deviations of pressure are between 0.09% and 0.28%, while the average absolute deviations of vapour phase mole fraction lay between 0.0020 and 0.0028. The results show that an azeotropic behaviour was observed for the binary system. (C) 2013 Elsevier Ltd. All rights reserved.