Pitch-based short carbon fibres were treated by both a gaseous oxidation and a cryogenic treatment approach. It was found by scanning electron microscopy that the fibre surface roughness was increased by various oxidative conditions, whereas the fibre diameter was reduced by the cryogenic treatment. In both cases, appropriate treatments could effectively improve the mechanical properties in their epoxy composites due to the enhanced fibre-matrix interfacial bonding. (C) 2004 Elsevier Ltd. All rights reserved.