Chlorella vulgaris and rice husk were selected from microorganisms and agricultural waste, respectively, to create new gold-eluteable adsorbents for adsorption of gold-thiourea complex, and compared with activated carbon. The maximum gold adsorption of heated-immobilised C vulgaris, heated rice husk, and activated carbon was 10.34, 28.22 and 35.88 mg Au/g adsorbent, respectively. FTIR spectrum, thermodynamic study and elution tests indicated that heated-immobilised C vulgaris and heated rice husk adsorbed gold by chemical adsorption: co-ordinate covalent bond. The active functional groups of heated-immobilised C vulgaris were ketone, carboxylate and ester, while the groups of heated rice husk were ketone, carboxylate and siloxane. Activated carbon mainly adsorbed gold by physical adsorption. Gold adsorbed onto heated-immobilised C vulgaris, heated rice husk, and activated carbon was able to be eluted by 0.5 M Na2S2O3 to 100, 87 and 41%, respectively. Although heated-immobilised C vulgaris had the highest eluteability, it adsorbed less gold. Therefore, heated rice husk could be used as an alternative adsorbent for gold-thiourea pre-concentration. (C) 2002 Elsevier Science Ltd. All rights reserved.