Decomposition and synthesis reactions of methyl formate are potentially useful for recover of the waste heat from factories and for air conditioning of residential areas. In this study, solubility of carbon monoxide in liquid methyl formate was measured to get fundamental data for designing a chemical heat pump system. The solubility of carbon monoxide in liquid methyl formate was measured for pressures between 0.5 MPa and 2.2 MPa and temperatures between 303 K and 373 K. Empirical correlations for the solubility, were derived by the method of least squares for the temperature and pressure terms. The results of the solubility measurement, demonstrated that the ratio of fugacity to mole fraction of carbon monoxide increases with the increase of temperature. Furthermore two empirical formulas of solubility characteristics were obtained as functions of the temperature and the total pressure or the partial pressure under vapor-liquid equilibrium conditions.