Abstract: The biosorption of radionuclide 241 Am on R.arrihizus from aqueous solution and the effects of the experimental conditions on the biosorption are investigated by the batch technique. The experimental results show that the R.arrihizus is a very efficient sorbent. The biosorption reaches equilibration in 1 h , the optimum pH range is 1～3. No significant temperature effect on 241 Am biosorption is observed in the range of 10～45 ℃. No significant differences of biosorption in the presence and absence of Au 3+ or Ag +are observed. The relationship between concentrations of 241 Am in aqueous solutions and adsorption capacities of 241 Am can be described by the Freundlich adsorption equation.