There is a increasing emphasis in today’s world to use environmental friendly solutions for tribological and lubrication purposes. Use of water as a lubricant presents a cost effective and easy method of bio friendly lubrication. But, as water has low viscosity, it is necessary that the materials used in water lubricated contacts perform exceedingly well in boundary lubricated conditions. Polymer Based Materials (PBMs), are one such group of materials which have been proven to perform well in such conditions. In particular, Ultra High Molecular Weight Polyethylene (UHMWPE) has been extensively used in water lubricated contacts. But, PBMs still suffer from wear and related problems and there is room for improvement. Various methods have been tried with mixed results to improve the qualities of polymers and consequently their performance in water lubricated contacts. One such method is by inclusion of fillers. Conventionally, micron sized fillers have been used to form composites with a polymer resulting in materials with better properties. Recently, nanometer sized reinforcements have been attracting more attention due to their unique mechanical and tribological properties. Combining micrometer and nanometer sized filler in a polymer composite could help form materials with excellent properties. Such composites would be termed as a hybrid material. Therefore, the aim of this project and thesis is to experimentally investigate the influence and interaction of micro and nano carbon-based fillers on tribological behaviour of UHMWPE composites and provide further understanding of the mechanisms involved.