Pore size and pore size distribution (PSD) govern effective adsorption amount, which is one of requisite properties as adsorbents in the practical applications. Although activated carbon (AC) offers remarkably high specific surface area, tailoring its PSD according to certain application, for example, narrowing the PSD, shall further enhance its superior adsorption performances. In this study, narrow PSD was challenged by attempting two-step activation process under various conditions/mixing methods using once-activated carbon as a starting material. AC with narrow PSD was successfully obtained by both slowing the heating rate and adopting solution impregnation method for second activation of the once-activated starting sample. Such expected effect was most probably attributed to more uniform distribution of activating agent on both external and internal carbon surfaces of the microporous starting sample.