A method using iodine has been developed for the stabilisation of low softening point (SP) pitch fibres that avoids air stabilisation in the production of carbon fibres (CF). The interaction between iodine and petroleum pitches has been studied by following the changes in the hydrogen content, aromatic or aliphatic, during the heat treatment of iodine-treated pitch fibres. Two low SP petroleum pitches were used and the iodine-treated pitch fibres were analysed by TGA, DSC, DRIFT, XPS and SEM. The results confirm that using this novel method pitches with low SP can be used to prepare CF with two advantages, compared with conventional methods. The stabilisation time is considerably reduced and treatments to increase the SP, usually required when low SP pitches are used to prepare CF, can be avoided. (c) 2006 Elsevier B.V. All rights reserved.