Polypropylene fiber and mercapto-modified polypropylene blend fiber (PPEVASH) were combined with carbon fiber as reinforcing elements in so-called hybrid epoxy composites. The impact performance and dynamic mechanical properties of these materials were investigated. Hybrid composites containing PPEVASH blend fibers display higher impact strength than plain carbon fiber composites but the performance is lower than plain PPEVASH-epoxy composite. The increasing of damping resistance and glass transition temperature, measured in terms of maximum damping temperature, of the hybrid EP/PPEVASH/CF composite may be attributed to several factors and include the interfacial adhesion PPEVASH fiber-matrix and PPEVASH-carbon fiber layers and the increasing of the crosslinking degree of the matrix, promoted by the presence of mercapto groups at the modified PP fiber surface. The presence of mercapto groups in the modified PP fiber also contributes for an improvement of the thermal stability, measured by thermogravimetric analysis. (C) 2000 Elsevier Science Ltd. All rights reserved.