Chitosanolytic activity was monitored using chitosan impregnated with Remazol Brilliant Blue R dye (RBB). Low-yielding chitosan (1%, w/v) hydrolysis was modelled using Viscozyme (R) L (50%, w/w), a commercial mixed-glucanase, and was found to perform optimally at pH 4.5 and 50 degrees C. The chitosanase assay was performed on powdered (RBB-P) and colloidal form (RBB-Q of the dyed chitosan. Hydrolysis of chitosan was accompanied by the release of water-soluble dyed-hydrolysate. which can be monitored rapidly using microplate reader at 595 nm. The result obtained from this method was in agreement with the determination of reducing end by using the traditional, complex and time-consurning DNS method. The method is significantly rapid and more sensitive than DNS method. (c) 2005 Elsevier Inc. All rights reserved.