Lipase from Aspergillus niger was used for the selective hydrolysis of the 3-O-acetate of cephalosporin C to give an intermediate useful for further chemical elaborations. This lipase was purified to homogeneity and its properties compared with previously published data that present some discrepancies. The lipase proved to be very effective in catalyzing 3-O-acetate hydrolysis and versatile toward substitution on the beta-lactamic ring. In fact, as an example, two other cephalosporinic derivatives, cephalotin and cefotaxime, were efficiently deacetylated. The lipase was immobilized on Eupergit C and employed continuously in either a column or a batch reactor for 2 months without appreciable loss of activity.