A method is presented for calculating the contribution that enthalpies make for every component of mixtures of activated carbon–water and activated carbon–hexane to the immersion enthalpy using the concepts that are used in the solution enthalpies. The immersion enthalpies of microporous activated carbon in water and in hexane have values from −18.97 to −27.21 and −25.23 to −47.89 J g−1, respectively. From the immersion enthalpies and mass relation of the activated carbon in each of the solvents, the differential enthalpies are calculated for the activated carbon in water, HwDIFac, with values between −15.95 and −26.81 J g−1, as are the differential enthalpies for the activated carbon in hexane, ΔHhDIFac, with values between −6.86 and −46.97 J g−1. For a low mass relation of the mixture components the contributions to the immersion enthalpy of the activated carbon and water differ by 3.20 J g−1, while the difference between the contributions of the activated carbon and hexane is 19.41 J g−1.