This project involves measurements of the vapor phase composition for the ethane + water binary system presenting phase equilibria near hydrate-forming conditions. The H2O + C2H6 binary system isothermal vapor phase data, concerning both vapor-liquid and vapor-hydrate equilibria, were measured at (278.08, 283.11, 288.11, 293.11, 298.11, and 303.11) K and pressures up to the ethane vapor pressure. In this work a static-analytic apparatus, taking advantage of a pneumatic capillary sampler (Rolsi, Armines' patent) developed in the Cenerg/TEP laboratory, is combined with an exponential dilutor for calibration purposes and a PVT apparatus to visualize and determine the hydrate-forming conditions. The six sets of isothermal P, y data are represented with the Peng-Robinson equation of state (PR-EoS) using the Mathias-Copeman alpha function and the Huron-Vidal mixing rules involving the NRTL local composition model (PR-EoS/MC-HV-NRTL). This equation (PR-EoS/MC-HV-NRTL) is also used to fit the available literature data. A Henry's law approach was selected to treat the aqueous phase.