To develop highly efficient adsorbents for water vapor that may be applicable in an adsorption heat pump (AHP), KOH chemical activation was applied to containing added melanine, in an attempt to keep as many hydrophilic functional groups as possible on te activated carbon. As a result, it was found that simple addition of melamine did not increase the number of hydrophilic functional groups. However, when phenol resin with chemically bound melamine was employed, the attachment of nitrogen on the active carbon was observed. Further, the number of hydrophilic functional groups was found to increase. Finally, the amount of water vapor adsorbed on the active carbon manufacutred was found to be 1.7 times higher than that adsorbed on silica gel, in the relative water vapor pressure range of an AHP in a closed system.