Using first principle calculations, we find that hole doping remarkably enhances adsorption strength of naphthalene on single-wall carbon nanotubes (SWNTs). The enhancement in adsorption strength is more significant for the larger-sized SWNTs, and the adsorption of naphthalene on the larger-sized (10,0) SWNTs becomes stronger than that on the smaller-sized (5,5) SWNTs at a higher doping level. However, the enhancement in adsorption strength appears insensitive to the electronic structure of SWNTs. For similar-sized SWNTs, hole doping does not reverse the selective adsorption of naphthalene towards metallic SWNTs versus their semiconducting counterparts. This is in sharp contrast to NH 2 CH 3 adsorption, where hole doping can reverse the selectivity of NH 2 CH 3 towards metallic SWNTs versus similar-sized semiconducting SWNTs.