Partially carbonized fibres, termed quasi-carbon fibres (QCF), with good thermal stability and acceptable mechanical properties were developed from a Polyacrylonitrile-based precursor. Heat treatment temperature (HTT), in the 400-950 degrees C range, played a major role in determining the thermal, mechanical and electrical properties of the QCF. The thermal stability of the QCF was increased by increasing the HPT. An appreciable amount of the graphite-like structure in QCF began to develop at ca. 650 degrees C. The Young modulus magnitudes of QCF scaled almost linearly with the pyrolysis temperature. In contrast, the QCF exhibited a decreasing trend in both tensile strength and failure strain up to a HTT of 650 degrees C, above which both the tensile strength and failure strain of the QCF increased with the HTT. Electrical resistivity values of the QCF covered a very wide range from 10(7) to 10(-2) Ohm cm. QCF showed semiconducting behaviours with activation energies falling between 0.690 and 0.0052 eV when the pyrolysis temperature was in the 400-850 degrees C range.