A method for preparing magnetic crosslinked chitosan microparticles was developed. The chitosan (CS) encapsulated magnetic particles were produced in alkaline conditions by in situ oxidation of the ferrous ions initially dispersed uniformly within the polysaccharide matrix. The polymer was then crosslinked using glutaraldehyde (GLA). The products were characterized regarding their size distribution and surface charge (by laser diffraction analysis, zeta-potential measurement, and conductometric titration), morphology (TEM), and magnetic properties (magnetic susceptibility analysis). The fact that the particles contain both magnetic iron oxide and chitosan was confirmed by FTIR and thermogravimetric analysis. The synthesis parameters were optimized for obtaining stable magnetic microparticles bearing surface amino groups that can subsequently be used for heavy metal ion complexation. The composite particles obtained by the optimum procedure had an average diameter of 40 mu m and a saturation magnetization of 24 emu/g, corresponding to about 47% magnetic iron oxide content.