Activated carbons have been wildly used as adsorbents for various purpose. When used in a cigarette filter activated carbon can selectively remove a number of the vapor phase compounds to varying degrees of efficiency. To improve the wet-feeling of cigarette smoke with AC in the filter, a new method is developed to chemically functionalize a coal-based activated carbon (AC) based on silanization reaction. Silanization using 3-glycidoxypropyltrimethoxy silane was performed after the oxidized AC was reduced by lithium aluminum hydride. N2 and water adsorption, FTIR, and XPS were employed to characterize the changes in the surface morphology, chemistry and physical conditions at different processing stages. Water content analysis in cigarette mainstream smoke (MSS) showed a positive result in the application of modified AC.