Carbon nanotubes (CNTs) were employed as adsorbent to study the adsorption characteristics of some divalent metal ions (Cu, Co, Cd, Zn, Mn, Pb). The effect of solution conditions such as pH and metal ions concentration was investigated. At pH 9 the affinity order of the metal ions towards CNTs is Cu(II) > Pb(II) > Co(II) > Zn(II) > Mn(II). The Freundlich adsorption model agrees well with experimental data. Our results suggest that CNTs have good potential application in environmental protection. (c) 2007 Published by Elsevier B.V.