This paper is related to study the using sea lettuce (Ulva lactuca) as a low-cost adsorbent for removing phenol compound from aqueous solutions by adsorption at different operating conditions in a batch unit. The SEM and FTIR tests were performed to determine the morphological characteristics and the functional groups existing on the adsorbent material respectively, while the surface area was identified by two ways which were blue color method and BET method. The results of the adsorption experiments showed that the efficiency of the removal process is inversely proportional with initial concentration of phenol, pH and temperature; while the efficiency was directly proportional with adsorbent amount, agitation speed and treatment time. The results showed that the percentage of removal of phenol from processed water solutions ranged from 25.446% to 90.125%. Langmuir and Freundlich isotherm models were chosen to esteem the amounts of phenol adsorption by the sea lettuce powder. The kinetic study shows that the adsorption was obeyed pseudo second order also the thermodynamic parameters were calculated.