The study investigated enzymatic pretreatment of oat bran, using Viscozyme L to enhance protein extraction. Response surface methodology (RSM) was used to study the effects of pretreatment variables of Viscozyme L concentration (6-30 FBG), pH (3.0-5.0), incubation time (0.5-2.5 h) and temperature (35-55 degrees C) on protein extraction from oat bran. The results indicated that the generated regression model represented the relationship between the independent variables and the responses. Protein extraction from oat bran was mainly affected by pH and incubation temperature. From the RSM-generated model, the optimum conditions of enzymatic pretreatment were identified as Viscozyme L concentration 30 FBG/10 g of oat bran, pH 4.6, incubation time 2.8 h and temperature 44 degrees C. Under the optimum conditions, the predicted protein extracted from oat bran was 55.7%, whereas, the experimental extracted protein was 56.2%. The RSM-predicted and experimental extracted proteins were not significantly different from each other. The enzymatic pretreatment method under the optimum conditions extracted significantly more protein (56.2%) than did the alkaline (pH 9.5) method (14.76%). Viscozyme L pretreatment of oat bran improved protein extraction. (c) 2007 Published by Elsevier Ltd.