Phase behavior properties of (bitumen + solvent) systems have a significant effect on surface upgrading methods and are necessary for the recovery of bitumen from reservoir. In this study, the phase partitioning and component distribution between phases as well as phase properties at equilibrium condition for the (Athabasca bitumen + ethane) system at room temperature were experimentally evaluated. The experiments were conducted using a designed pressure-volume-temperature (PVT) apparatus to obtain liquid- liquid equilibrium properties as well as extraction yield for (bitumen + solvent) systems. In addition, the equilibrium k-value for each component present in the mixture at equilibrium condition was calculated on the basis of compositional analysis of liquid phases and available correlations for the molecular weight of heavy components. The impact of pressure and solvent to bitumen ratio on the boiling point curves and compositional analysis of flashed off liquids as well as equilibrium k-values were evaluated. Finally, the molecular weight of flashed off liquid phase samples were estimated on the basis of molecular weight and compositional analysis of liquids.