The properties of siliceous mesostructured cellular foams (MCF) with the surface functionalised using different organosilanes to immobilize covalently trypsin have been studied. Four organosilanes were applied: 3-aminopropyltriethoxysilane, 2-aminoethyl-3-aminopropylmethyldimethoxysilane, 2-aminoethyl-3-aminopropyltrimethoxysilane and 3-glicydoxypropyl-triethoxysilane. The samples modified using alkylamines were further activated with glutaraldehyde (GLA), a cross-linker. Commercially available silica gels and Eupergit C were used for comparison. Activity of MCF-based biocatalysts expressed in BAPNA and casein conversion, was significantly higher than of the silica gel- and Eupergit C-based counterparts. In the best systems the determined activity of trypsin was higher than of a free enzyme. The GLA-amino linkages appeared the most effective systems for the covalent immobilization of trypsin. The MCF-based preparations were notably more stable than a native enzyme at 333 K and they also showed good storage stability at 277 K. A unique porous structure of MCF was found to be a critical factor which renders siliceous mesostructured foam a very promising material for immobilization of enzymes. (c) 2007 Elsevier B.V. All rights reserved.