beta-Glucosidase from Penicillium funiculosum was immobilized on nylon powder previously activated with triethyloxonium tetrafluoroborate, 1,2-diaminoethane and glutaraldehyde. The activation of the nylon powder and the immobilization processes were studied and optimized for the enzyme and the matrix. A high activity retention (67%) was obtained using the activation and immobilization conditions finally selected.