Background: Phenol has been classified as hazardous pollutant and its presence in natural water is considered as a serious threat to human health and overall water quality.  The major source of phenol pollution in the aquatic environment is wastewater from petroleum and petrochemical industries. Objective: This study aims to investigate the adsorption efficiency of granular activated carbon (GAC) and activated carbon prepared from rice husk (RHAC), a low-cost agricultural by product, in removing phenols from simulated wastewater. Methods: Batch adsorption studies were conducted to study the effect of various parameters such as initial concentration, agitation time, adsorbent dose and solution pH on phenol removal. Equilibrium data were analyzed by the Langmuir, Freundlich, Temkin and Hurkin-Jura. The adsorption kinetics were studied using the pseudo-first-order and second-order kinetics models. The mechanism of the adsorption process was determined from the intraparticle diffusion model. Results:  The efficiency of GAC and RHAC on removal of phenol was 95% and 90% respectively at an agitation time of 6 hr, a pH 6,150 rpm, an adsorbent dose of 5 g/L, initial phenol concentration of 50 mg/L and a temperature of 20ºC. Acidic pH was more favorable for the removal of phenol.  Increasing initial concentration of phenol decreases the percentage removal. The adsorption isotherm models fitted the data in the order: Freundlich > Langmuir > Tempkin isotherms. The pseudo-second-order kinetic model best described the adsorption process Conclusion: The results showed that the prepared activated carbon was an effective adsorbent for removal of phenol as a low-cost and an alternative adsorbent.