The effectiveness of xylanase as a prebleaching agent has been established on a commercial scale. The efficiency of bleaching improves with the enzyme treatment but it varies with the pulping method and pulp raw material. In the present work, crude xylanase from Bacillus coagulans has been characterized with respect to the operational parameters and the stabilities at various pH values. Xylanase from B. coagulans has been tested on three non-woody pulps as a prebleaching agent. The effects of crude enzyme on wheat straw, rice straw and jute pulps at two different initial pH of pulp have been studied and a maximum brightness gain of 5.1 points has been achieved with rice straw pulp at an initial pH value of 8.5. In the case of wheat straw and rice straw pulps, maximum brightness gain has been obtained at the higher pH values. (C) 2005 Elsevier Ltd. All rights reserved.