The solubility Of CO2 in the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and the liquid-phase molar volume were determined, in a precision high-pressure PVT apparatus, for water mass fraction of [bmim][PF6] ranging from 0.0067 % to 1.6 % and over temperature and pressure ranges of (40 to 60) 14 degrees C and (1 to 25) MPa. The deviation in solubility, at the same temperature and pressure, with different water mass fractions was not more than 15 %, and the average is 6.7 %. Solubility pressures were correlated with an 144 average relative uncertainty of about 1 % by means of the extended Henry's law for all water mass fractions investigated at less than 6 MPa.