Gas-expanded liquids offer many advantages as superior solvents for asymmetric hydrogenation reactions. To implement such applications, knowledge of the phase behavior of hydrogen with these tunable solvents is imperative. Phase boundary data are reported for the ternary system of carbon dioxide, methanol, and hydrogen at 313.2 K and pressures up to 21.7 MPa. The data were measured in a variable-volume windowed vessel by visual observation of one- to two-phase transitions.