The removal of zinc from aqueous solution by adsorption on Ulva fasciata sp. was studied as a function of contact time, pH of the solution, metal ion concentration, adsorbent concentration and adsorbent size. Batch experiments results showed that the adsorptive capacity of U. fasciata sp. was 13.5 mg/g of adsorbent. The Langmuir and Freundlich models were used to describe the adsorption equilibrium of zinc on U. fasciata sp. and the adsorption followed the Langmuir isotherm. The Langmuir and Freundlich constants for adsorption of zinc on U. fasciata sp. were determined. The pseudo first and second order rate expressions were used to correlate the experimental data. The kinetic constants were determined for both the models and the second order rate expression was found to be more suitable. (c) 2006 Elsevier B.V. All rights reserved.