The biosorption of Ni(II) from aqueous solution by using Enteromorpha as cheap green alga were considered. The effects of pH, temperature, contact time, initial concentration of Ni(II) and biosorbent dose were studied. This study shows that Enteromorpha can be used for removal of Ni(II) from aqueous solution wastewater. A second-order equation designated for kinetic of the biosorption and Langmuir isotherm model are fitted for equilibrium of the adsorption data.