Abstract: The potential of pre-treated Turbinaria conoides algal biomass to adsorb As (III) and As (V) from aqueous solutions was investigated in batch biosorption experiments. The process parameters studied include the solution pH, initial metal ion concentration, rate of agitation and sorbent dosage. It was seen that lower pH favours more adsorption for both the arsenic species (40 mg g-1 of As (III) and 42 mg g-1 of As (V) at pH 2 and the maximum uptake of the metal ions by the algae is obtained at lower concentration of metal ions and higher sorbent dosages. Also, the metal uptake was maximum at an agitation speed of 150 rpm and decreased beyond it. Equilibrium studies reveal that Langmuir isotherm model (Qmax = 20.2421 mg g-1 for As(III) and 25.9747 mg g-1) provides the greatest accuracy in describing the adsorption when compared to Freundlich and Redlich Peterson models. The sorption kinetics of arsenic could be modelled well by the Elovich equation than the Lagergren and Intraparticle diffusion models.