In this experiment, we use activated charcoal sample as adsorbent and iodine as adsorbate. Adsorption of iodine will determine the surface area of activated charcoal. This method can be applied in determination of the surface area of powder drug in pharmaceutical industries. The surface area is very important in field of pharmacy where it is one of factor that affects the rate of dissolution and bioavailability of drugs that are absorbed in gastrointestinal tract.