The immobilization of lactase (β-galactosidase) enzyme was achieved by entrapping it in chitosan-alginate composite scaffolds, which were formed by ionotropic pre-gelation followed by a pH increase to synthesize polyelectrolyte complex scaffolds, and subsequent cross-linking and activation by glutaraldehyde. The operational stability upon storage of the enzyme entrapped was checked by performing batch hydrolysis of lactose concentrations ranging from 1mg/ml to 5mg/ml and the resulting glucose produced in every reaction was determined using the glucose oxidase-peroxidase assay. This study also investigates the stability of the free and immobilized enzymes at altered sets of pH and temperature at a fixed concentration of enzyme for the reaction medium. Morphology and structure characterization of lyophilized composite scaffolds were examined using scanning electron microscope and Fourier transform infra-red spectra, respectively. © RJPT All right reserved.