Immobilization of a commercial cellulase (C) onto chemically modified pumice (P) particles has been studied. ZrOCl2 activated pumice was used as a carrier for the cellulase immobilization and some operational properties of this carrier were determined. Denim washing performance of immobilized cellulase (MP) was also investigated comparing with free enzymes (FE) and traditional denim washing procedure. Immobilized acid cellulases can efficiently abrade indigo dyed denim fabrics. (C) 2004 Elsevier Ltd. All rights reserved.