Two enzymes, lipase and β-galactosidase, have been encapsulated within sol-gel matrices. Enzymatic activity of encapsulated lipase for hydrolysis and trans-esterification reactions is maintained. Encapsulation yields depend not only on the sol-gel porous texture but also on the water amount added for the sol-gel synthesis and the hydratation history of the enzyme. When the water amount is low, the highly active enzyme conformation generated by the phase separation is frozen during gelation. Escherichia Coli have been also encapsulated. The cellular organization appears to be well preserved. Their β-galactosidase activity seems to be better in wet gels but decreases dramatically upon drying.