The organic Rankine cycle (ORC) is one solution to recover energy from high temperature hot sources. It requires working fluid with high critical coordinate values. It is named for its use for an organic high molecular masse fluid with a liquid-vapor phase change. The knowledge of phase diagram of working fluid is a crucial task in refrigeration process. In this context, a new mixture of decafluorobutane (R3110) and 1,1,1,3,3-pentafluorobutane (R365mfc), is studied by means of experimental measurements and modeling procedures. The purpose is to obtain the isothermal vapor-liquid equilibrium data (R3110 + R365mfc) of binary system ranging from (333.26 to 441.61)K temperature, and (0.2016 to 3.0927) MPa pressure. The data were obtained with accurate within u(T, k=2)=0.02 K, u(P, k=2)=0.0003 MPa and u(z)=0.004 for molar composition. In the present work, the static analytic method is another time investigated to achieve a high quality data as it was largely demonstrated previously by the team of our laboratories. The experimental data are correlated using the classical equations: Peng-Robinson equation of state, the Mathias-Copeman alpha function, and the Wong-Sandler mixing rules involving the NRTL model. The predicted critical line is well reproduced. (C) 2013 Elsevier B.V. All rights reserved.