The lack of published data on the chemical structures of lubricants makes it almost impossible to investigate the influence of structure on lubrication properties. In this investigation, the lubricating properties of three esters with known chemical structure have been investigated and compared with a commercial ester. The lubrication properties that were expected to be dependent on chemical structure such as film thickness and traction, viscosity and friction coefficients were compared by experiment. To measure the film thickness a Ball and Disc Apparatus was used, the traction coefficient was measured in a Jumping Ball Apparatus, the viscosity in a rotational cylindrical viscometer and the friction coefficient in a reciprocating friction and wear test apparatus. The results showed that molecular length has a significant influence on lubrication properties, with longer molecules giving the highest viscosity and greatest film thickness. The length of the molecule did not influence the coefficients of friction, but the traction coefficient, Υ, decreased with increasing molecular length.