Poly(vinyl alcohol) cross-linked with para-formaldehyde (PVA-F) and natural polysaccharide-chitosan in bead form and salicylic acid-resorcinol-formaldehyde polymeric resin (SRF) in powder form were used for immobilization of beta-galactosidase through covalent linkages. Various activation processes and conditions were optimized. Immobilized enzyme showed very good storage stability at room temperature. Durability of the enzyme was also improved on immobilization. On repeated use of enzyme immobilized on chitosan beads, no loss was observed in enzyme activity even after 10 batches. Michaelis constant K-m and maximum reaction velocity V-m were calculated for free and immobilized enzyme systems. Effect of pH and temperature on enzyme activity was estimated and energy of activation (E(a)) and inactivation constant (K-i) for free and immobilized enzyme were calculated.