In the present work removal of an azo dye (Reactive Black 5) was investigated from aqueous solution by adsorption onto scallop as a low-cost and widely available adsorbent. The effect of various operational parameters, such as contact time, pH, initial dye concentration and adsorbent dosage on the removal efficiency of dye was studied. Removal efficiency declined with the increase in solution pH and initial dye concentration but with the decrease in adsorbent dosage. Experimental equilibrium and kinetics data were fitted by Langmuir and Freundlich isotherms and pseudo-first-order and pseudo-second-order kinetic models, respectively. (C) 2013 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.