The adsorption of a large reactive dye, Reactive Black 5 dye, onto two bamboo based active carbons using phosphoric acid in a two stage activation process and three conventional adsorbents, carbon F400, bone char and peat, has been studied. The monolayer saturation adsorption capacities for Reactive Black 5 were determined by the Langmuir isotherm analysis and are: 176, 157, 7, 447 and 545 mg dye/g adsorbent for active carbon F400, bone char, peat, bamboo carbon (2123 m(2)/g) and bamboo carbon (1400 m(2)/g), respectively. The equilibrium experiments were analysed using three isotherms, Langmuir, Freundlich and Redlich-Peterson and the based on the lowest SSE values, the Redlich-Peterson was the best fit correlation. The effect of adding salt, in the form of sodium phosphate, on the adsorption capacities has been studied and was found to increase the adsorption capacities of both bamboo carbons to over 900 mg/g. (C) 2009 Elsevier Inc. All rights reserved.