The highest production of α-L-arabinofuranosidase by Penicillium janczewskii in medium with brewer's spent grain and orange waste was observed when cultivation was carried out in pH 5.0 at 25°C, for 8.5 days under shaking. The α-L-arabinofuranosidase present in the crude filtrate was optimally active at 60°C and pH 4.0; it was stable in a wide range of pH, maintaining 90% of the activity from 2.0 to 8.0. The enzyme was very stable at 40°C, maintaining 90% of the activity within 1 h. The estimated half-life at 50°C was 10 min, and at 60 and 70°C, it was 5 min. This enzyme was activated in the presence of Ba 2+ , Ca 2+ , Mn 2+ and NH 4 + while the ions Pb 2+ , Mg 2+ , Hg 2+ , Co 2+ and Cu 2+ , as well as PMSF, DTT, βmercaptoethanol, EDTA and SDS inhibited it.