Carboxymethylated-bacterial cellulose (CM-BC) was synthesized by Acetobacter xylinum by adding water-soluble carboxymethylated cellulose (CMC) in the culture medium. The CM-BC was examined for the removal of copper and lead ions from aqueous solution compared with BC. The effects of performance parameters such as pH, adsorbent dose, contact time on copper and lead ion adsorption were analyzed. Both BC and CM-BC show good adsorption performance at optimized pH 4.5. Compared with BC, CM-BC performs better adsorption, with the value of 9.67 mg (copper)/g, 22.56 mg (lead)/g for BC and 12.63 mg (copper)/g, 60.42 mg (lead)/g for CM-BC, respectively. The adsorption rate closely follows pseudo-second-order rate model and the adsorption isotherm data well follows the Langmuir model. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.