In the present study, adsorption of three metal ions Pb(II), Hg(II) and Cd(II) on carbon aerogel a new form of activated carbon has been investigated in mono- and multi-component (binary and tertiary) system. Batch experiments were also carried out for mono- and multi-component systems with varying metal ion concentration (mg/l) to investigate the competitive adsorption characteristics. Many adsorbents have been studied for their adsorption properties pertaining to mono-component solutions of metal ions. However, to treat wastewater with new materials, their performance needs to be ascertained in multi-component system. The scanning electron micrographs (SEM) and EDAX spectrum of carbon aerogel surfaces before and after the adsorbent was equilibrated with the metal ion solution clearly establishes the presence of the metal ions and some surface modifications can be observed on the carbon aerogel particles adsorption with (i) surface chemistry of the pellets on the surface of carbon aerogel and (ii) inside layers of the carbon aerogel. Applicability of the isotherm models namely Freundlich and Langmuir to predict the equilibrium uptake of Pb(II), Hg(II) and Cd(II) in mono-component, binary and tertiary system has also been tested. Langmuir and Freundlich models are found to generally represent the experimental though but not consistently. (c) 2007 Published by Elsevier B.V.