It is known that the use of natural gas as a vehicular fuel is advantageous, but the storage limitation of natural gas is a severe drawback to the use. In this paper, a method for storing natural gas at moderate temperatures and pressures by dissolving natural gas in solvents is studied. A set of experimental equipment for measuring gas solubility in liquids under high pressures was established. The solubilities of methane in heptane + cyclohexane and heptane + ethanol were measured over the temperature range from 291.15 K to 313.15 K and pressures to 12.00 MPa. The new solubility measurements are believed to have uncertainties of 0.002 in the mole fraction. The data were analyzed using the Peng-Robinson equation of state with two kinds of mixing rules. In general, the equation coupled with the simple mixing rule represents the experimental data of methane + heptane + cyclohexane well over the complete temperature and pressure range when the interaction parameters k(ij) for methane + heptane and methane + cyclohexane were used and the k(ij) for heptane+cyclohexane was ignored. Owing to the polarity of ethanol, when the experimental data of methane + heptane + ethanol were calculated by the equation, besides the interaction parameters k(ij) for methane + heptane and methane + cyclohexane, the interaction parameter for heptane + ethanol as well as an additional interaction parameter, l(ij), must be employed. At the same time, the molar volumes of liquid-phase mixtures at high pressures for two kinds of ternary systems were measured and calculated.