To design efficient polymeric supports for lipase immobilization, two series of hydrogels based on acrylamide and three methacrylates were prepared via crosslinking with ethylene glycol methacrylate and N,N-methylenebisacrylamide. The three methacrylates used to prepare these hydrogels had different alkyl chain lengths: C-1 (methyl methacrylate), C-12 (dodecyl methacrylate), and C-18 (octadecyl methacrylate). In the reaction scheme, only the feed concentration of the hydrophobic component (methacrylate) was varied. The characterization of the hydrogels was carried out with Fourier transform infrared, scanning electron microscopy, and nitrogen analysis to establish their structural aspects and to obtain evidence for network formation; the swelling and water uptake of the hydrogels were studied as functions of the time, temperature, and pH. Lipase immobilization on selected hydrogels was studied as a function of the concentration of the methacrylate used in the feed and the nature of the crosslinker. The activity of the hydrogel series that showed the highest activity of the immobilized lipase was investigated further as a function of the methacrylate feed concentration, pH, and temperature. Some organic solvents were studied to investigate the effect of the nature of the solvent on the activity of the immobilized lipase. The activity of the immobilized lipase was more than that of the free lipase and was affected by the structural attributes of the polymeric supports and by the nature of the solvent. (C)) 2007 Wiley Periodicals, Inc.