In this work, biosorption of Cr(III) by the marine brown algae Sargassum muticum was studied in a batch system. Kinetics and equilibrium experiments were conducted at different pH. Equilibrium data are well described by the Langmuir and Langmuir-Freundlich isotherms. The two mass transfer models give comparable results, but they did not provide a perfect representation of the sorption data. Sargassum muticum was compared with the brown algae Laminaria hyperborean and the red algae Gelidium sesquipedale, showing maximum uptake capacities of, 56 ± 3, 70 ± 4 and 18 ± 1 mg Cr(III) g<sup align="right"> -1 , at pH = 5, respectively.