An investigation is described in which the morphology of hemp stem was examined by optical and scanning electron microscopy. We reported the results concerning steam-explosion treatment either on bast fibers impregnated with alkaline liquor or on woody hemp chenevotte samples impregnated under neutral, acidic and alkaline conditions. The influence of steam-explosion treatment parameters were followed by optic and scanning electron microscopy, chemical composition and evolution of the average (DPv) values of the purified samples. Hemp bast fibers purified by steam treatment were compounded with polypropylene (PP), either directly or after surface treatment with polypropylene-maleic anhydride co-polymer (PPMA). Polypropylene/hemp fibers composite films with various amount of fibers were prepared and their mechanical properties were improved, in particular when fibers treated with PPMA were used. Copyright (C) 1997 Elsevier Science Ltd.