Phenol is an environmental pollutant; the present study was conducted to examine the adsorption of phenol by rice straw. For this purpose raw (untreated), physically treated (boiled and dried) and thermally treated (heated at 230°C for 3 h to produce ash) rice straw were selected to determine phenol removal efficiency at different contact times and adsorbent dosages for 1 and \1 mm rice straw particles. Residual phenol concentrations were determined by colorimetric method. Highest 84 % of phenol removal was observed for thermally treated \1 mm rice straw particle. Equilibrium time was more than four hour. Percentage of removal of phenol increased as the adsorbent dose increase. The removal efficiency increase in the order of: raw rice straw \ physically treated \ thermally treated (ash) rice straw. Langmuir and Freundlich isotherm was developed for 1 and \1 mm particle size of thermally (ash) treated rice straw. Freundlich isotherm best fit the equilibrium data for 1 mm thermally treated rice straw. The results showed that thermally treated rice straw (ash) can be developed as a potential adsorbent for phenol removal from aqueous solution.