Diesel fuel adulteration is a growing challenge in Nigeria as it is associated with engine performance issues, high environmental pollution and loss of revenue accruable by the government. This problem is, however, not unique to Nigeria, it is also prevalent in many developing countries. In determining the physiochemical properties of fuel samples, sensor-based techniques, H Nuclear Magnetic Resonance (H NMR), gas chromatography-mass spectrometry coupled with statistical methods have all been used to investigate the level of adulterants that are present. An Agilent 7890B Series Gas Chromatograph (GC) linked to an Agilent 5977B Mass Selective Detector (MSD) was used in the analysis, allowing detailed information of the composition of the four samples analysed to be obtained. The physio-chemical analysis showed differences in some parameters compared with international standards. The GC-MS analysis revealed the presence of volatile organic compounds such as benzene, toluene, and xylenes. A study of the physio-chemical properties of locally refined diesel can provide elementary data which can be used by local authorities and regulatory agencies to formulate appropriate policies.