The aim of the project was to develop a much-improved procedure for the determination of polycyclic aromatic hydrocarbons (PAHs) in used lubricants using up to date techniques and instrumentation and to then study their formation in a range of commercial lubricants. Analytical procedures have been developed, a method using basic laboratory GC, HPLC instrumentation and a procedure using more complex analytical instruments including multidimensional chromatography. This includes an investigation into sample clean up and extraction techniques including solid phase extraction (SPE), multidimensional chromatography and a study of lubricant degradation process. A model bench top engine lubrication system has also been developed to study the formation of PAHs in automotive and industrial lubricants containing various additives. These data has provided an understanding of the role of lubricant components in the formation of PAHs. The much improved rapid and efficient GC and HPLC methods for the analysis of PAHs in used lubricants has proved essential for understanding the contribution from operating conditions and industrial processes to the formation of PAHs under a range of engine conditions. A further study has examined the influence of additives in lubricants on the occurrence of PAHs. A bench top lubricant cycling system was developed. Standard engine lubricant basestocks and additives were cycled within this lubricant cycling system to establish the effects of temperature on individual basestocks and standard engine additives for the formation of PAHs. It was found different basestocks influenced the formation of PAHs under varying temperature conditions. Further work is required to assess the individual engine oil additives.