Carbon nanofillers, such as carbon nanotubes, graphite nanoplatelets and carbon black, are capable of transferring their excellent conductivity to a polymer whilst also enhancing or maintaining its original mechanical and thermal properties. Polymer/carbon nanofiller composites are increasingly finding applications in aerospace, automotive and electronic industries for antistatic protection, electrostatic dissipation and electromagnetic interference shielding etc., when flexibility or light weight is required. In recent years, much work has been carried out on the preparation and characterisation of polymer/carbon nanofiller composites. The influence of processing on the structuring and properties of polymer nanocomposites has had much less attention yet this is a critical aspect of nanocomposites research. The main aim of this work was to investigate the process-structure-property relationship of polymer/carbon nanofiller composites. The melt-mixed high density polyethylene /carbon nanofiller composites were processed by compression moulding, biaxial stretching and blown film extrusion, and the structure and properties of the resulting composites were characterised and analysed.