Finely ground rice husk was used as a filler in two commercial grades of polypropylene (PP) in different amounts. Rice hush powder was chemically treated with dilute hydrochloric acid, dilute sodium hydroxide solution, and dimethyl sulfoxide. The mechanical, thermal, and rheological properties of PP filled with untreated and treated rice husk powder were determined. Effectiveness of PP grafted with acrylic acid, PP-g-AA, as a compatibilizer was examined. Rice husk powder treated with acid showed significatn improvement in the flexural modulus of PP and also less water absorption. (c) 2008 Wiley Periodicals, Inc.