A high-pressure view-cell technique based on the synthetic method was used to determine the solubility of carbon dioxide in the ionic liquid 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][CH3SO4]). The temperature ranged from 293.2 K to 413.1 K, the pressure and the carbon dioxide molality reached up to similar to 10 MPa and similar to 3.3 mol of CO2 center dot(kg of [bmim][CH3SO4])(-1), respectively. The (extended) Henry's law was successfully applied to correlate the solubility pressures. The final results for the Henry's constant (at zero pressure) of carbon dioxide in [bmim][CH3SO4] (on the molality scale) are correlated within the estimated uncertainty (+/- 1.3 %) by ln(k(H,CO2)((0))/MPa) = 7.2738 - 1775/(T/K) - 0.002033(T/K). Furthermore, some small corrections were applied to the experimental results for the solubility of carbon dioxide in the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) reported in previous work. The corrected values for the Henry's constant of carbon dioxide in [bmim][PF6] only slightly and systematically deviate (by about -2 % at given temperature) from the values reported previously.