A high-pressure analytic phase equilibria setup, capable of operation at 150 degrees C and 30MPa, was developed. The variable-volume view cell contains two height-adjustable samplers enabling simultaneous sampling from two phases. Concurrent analysis of both samples was performed with dual online gas chromatography (GC). The GC comprises two inlets, four columns, two switch valves, and three detectors, arranged in parallel pathways. Quantitative detector calibrations were used. The setup was validated by sampling from a one-phase ternary of known composition, and comparison with binary and ternary literature data. The setup produces accurate phase composition data for supercritical systems and is well-suited to handle mixture constituents ranging from volatile gases to mid-length hydrocarbons.