The Kluwak shell has a Ca content of 28.31% so it can be used as an adsorbent in adsorbate adsorption. This study aims to determine the effect of activator KOH 3M and H3PO4 2.15 M on the surface area of the adsorbent (activated carbon of kluwak shell). The surface area was determined by the methylene blue adsorption method according to SNI 06-3730-1995. The test method was methylene blue 50 ml with a concentration of 100 ppm plus 0.15 grams of adsorbent at a shaker speed of 250 rpm, for 90 minutes. The filtrate is an adsorption solution that has been separated from the adsorbent whose concentration was tested using UV VIS at a wavelength of 625 nm. The absorbance obtained is converted to concentration using Lambert Bee's law, which is a linear relationship between absorbance and the concentration of a substance that absorbs in the form of concentration (Ce). The results of this study indicate that the surface area of activated carbon from the kluwak shell activator KOH 3M is larger than the surface area using H3PO4 2.15M. The surface area of activated carbon of the activated kluwak shell with KOH 3M was 155.526 m2/g and activated carbon of activated carbon with H3PO4 2.15 M was 62.536 m2/g.