With the aim of improving the performance of calcium alginate (Ca-Alg) hydrogel, a small quantity (5% of dry mass of sodium alginate) of hydroxyethyl cellulose (HEC) was used to associate sodium alginate to form interpenetrating networks (IPNs). Swelling results and mechanical stability tests showed that the formation of IPNs considerably restrained dried samples from swelling in 0.9% sodium chloride aqueous solution and reinforced the mechanical strength of microspheres. For emulsion droplets as template, microscopy showed that the original emulsion templating method employed in preparation of macroporous Ca-Alg microspheres was also applicable in the IPNs system. As for bovine serum albumin molecules as template, Alg/HEC microspheres showed a better recognition effect than that of Ca-Alg microspheres. The reduced network mesh size and strengthened cross-linkages in IPNs are responsible for these results. (C) 2005 Elsevier B.V. All rights reserved.