Olive oil, which is rich in oleic and linoleic acids, has been a major component of the Mediterranean diet for thousands of years and is known to exert a protective effect against various types of cancers and cardiovascular diseases. Therefore, oil consumption has been constantly increasing worldwide. The chemical composition of this food of plant origin depends on many factors, e.g. olive oil type and climatic, agronomic, cultivation, production and storage conditions. An extensive and updated list of the analytical techniques for the certification of authentic oils is known. It is preferable to combine various analytical tools with multivariate chemometric analysis to trace the geographical provenance of oils. Adequately selected appropriate analytical methods/techniques coupled with complex computational systems are helpful in the classification of olive oils and oilseeds with respect to their authentication/adulteration. The most common instrumental analytical tools applied in investigations of oil products are various spectrometric techniques/methods. Multivariate analysis has been mostly recommended and often used to evaluate olive products in terms of their geographical origin, cultivar identification, etc. The results obtained allow the identification of mislabelled products. The application of chemometric tools provides a deeper and wider understanding of the distribution of chemical elements in oils and oilseeds, which is highly important for correcting their classification.