Recent industrial InterestIn the low-temperature high-pressure processing of hydrocarbons has Increased the need for reliable data on the components found In natural gas. The objective of the work reported here is to provide accurate experimental measurements on a system of Industrial Interest and to assess the feasibility of modeling the phase equilibria with simple cubic equations of state. Liquid-vapor equilibria were measured for the binary systems N2 + C2H, and CH4 + C2He and the ternary system N2 + CH4 + C2He at 260.00, 270.00, and 280.00 K over the pressure regions of Industrial Interest. The data at 270.00 K were modeled with three cubic equations of state: the Peng-Roblnson equation, the Soave modification of the Redllch-Kwong equation, and a modified Clausius equation. All of the equations gave satisfactory results at lower pressures, but all failed to model the data satisfactorily near the critical points of the binary and ternary systems.