Calcium sulfite waste was successfully transformed to hydroxyapatite (HAp) by oxidation using H2O2, followed by reaction with (NH4)(2)HPO4 under an NH4OH atmosphere. A single phase hydroxyapatite was obtained by stirring at 60, 80, or 100 degrees C rather than by hydrothermal treatment at 150 degrees C. Such formation implied that the homogeneity of the solution was very important. The primary HAp particles obtained had columnar shape, which formed spongy secondary particles with a diameter of around 1 mu m. Such porous particles resulted from the dissolution rate of calcium sulfite. The HAp obtained had a relatively Ca-rich composition of around Ca/P=1.71, and the specific surface area was around 69 m(2)/g. In adsorption tests for Cs+ and Cd2+ cations in artificial seawater, the prepared HAp, like the general HAp powder, could remove Cd2+ cations from the seawater. (C) 2012 Elsevier B.V. All rights reserved.