The surface structure and morphology of several high strength polyacrylonitrile (PAN) based carbon fibres was studied with the scanning electron microscope (SEM) on the micrometre scale and the scanning tunnelling microscope (STM) down to the atomic scale. In addition, active surface area measurements were made to determine the number of bonding sites/unit area. Prior to the observations, the surfaces of some of the samples were subjected to either the commercial surface treatment or to oxidation in air or ozone in our laboratory. The roughness and number of bonding sites on each fibre surface was determined. These values will be correlated with the mechanical properties of composites made with these fibres and thermoplastic polymers in Part III of this study.