Isothermal vapor-liquid equilibrium (VLE) data for the system of hexafluoroethane (R-116) + n-butane are reported in this paper. The measurements were undertaken at six different temperatures ranging from 273.27 to 323.19 K, with pressure ranging from 0.104 to 3.742 MPa. Two of the temperature sets were measured below, and the remaining four were measured above, the critical temperature of R116. The measurements were performed in a "static-analytic" type VLE apparatus. The sampling of the equilibrium phases was performed via pneumatic ROLSI capillary samplers (Armine's patent). The equipment was developed in the CEP/TEP laboratory at MINES ParisTech. Combined expanded uncertainties in the measurements were estimated to be 0.02 K for temperature, 0.0006 MPa for pressure, and maximum of 0.004 for composition, based on the NIST guidelines. Each set of isothermal vapor liquid equilibrium data was correlated with the Peng-Robinson equation of state (PR-EOS). The Mathias-Copeman alpha function, and the Wong-Sandler mixing rule, utilizing the nonrandom two-liquid activity coefficient model, were incorporated into this equation of state.