Effect of activating procedure on the physic-chemical properties and adsorption performance of activated carbon was investigated. For this, pomegranate peel was used as biomass and carbonized to prepare base material. Activating process was carried out using traditional (sulfuric acid as activating agent) and green way methods (water as activating agent). SEM, FTIR and particle size analysis were conducted to characterize as-prepared biosorbents. The adsorption capacity of carbonized pomegranate peel, acid-activated carbon and water-activated carbon were measured through separation of pyridine from aqueous solution. The effect of initial concentration and solution pH was also studied for all samples. Results depicted that water activated carbon achieved maximum value of adsorption capacity among three adsorbents at the other equal conditions. Additionally, kinetic studies were conducted to find predicting model for each adsorbents. According to the results, pseudo second order model can be applied for all three kinds of biosorbents at certain adsorption conditions.