In recent decades, beta-xylosidases have been used in many processing industries. In this work, the study of xylosidase production by Penicillium sclerotiorum and its characterization are reported. Optimal production was obtained in medium supplemented with oat spelts xylan, pH 5.0, at 30 degrees C, under stationary condition for six days. The optimum activity temperature was 60 degrees C and unusual optimum pH 2.5. The enzyme was stable at 50 and 55 degrees C, with half-life of 240 and 232 min, respectively. High pH stability was verified from pH 2.0 to 4.0 and 7.5. The beta-xylosidase was strongly inhibited by divalent cations, sensitive to denaturing agents SDS, EDTA and activated by thiol-containing reducing agents. The apparent V(max) and K(m) values was 0.48 mu mol PNXP min(-1) mg(-1) protein and 0.75 mM, respectively. The enzyme was xylose tolerant with a K(i) of 28.7. This enzyme presented interesting characteristics for biotechnological process such as animal feed, juice and wine industries.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)