The char derived from the fast pyrolysis of macro-algae biomass, a brown alga Undaria pinnatifida, proved to be useful for the removal or recovery of copper from aqueous solutions. Even at a low dose of 0.1 g char/L, a high adsorption capacity was obtained. Physical activation with steam enhanced the adsorption of Cu, but chemical activation with a KOH solution decreased the adsorption capacity. A pseudo-second order kinetic model was used to explain the adsorption kinetics. The physically-activated char showed a Langmuir type of isotherm, and had a maximum adsorption capacity of 125.85 mg Cu/g. Based on the adsorption capacity, even at a low copper concentration, the char derived from the fast pyrolysis of U. pinnatifida is a valuable adsorbent for recovering copper from aqueous solutions. (C) 2012 Elsevier B.V. All rights reserved.