Adulteration of high quality edible oils and fats with those of lower quality has been a problem for many years. Before the advancement of modern analytical methods, quality checks of edible oils included a series of time consuming physical and chemical tests, whereas modern methodology is based on spectroscopic and chromatographic techniques coupled with chemometric methods. In this work the usage of FT-IR combined with numerical methods for qualitative and quantitative detection of adulteration in binary and ternary mixtures of olive oil with rapeseed oil, sunflower oil and high-oleic sunflower oil was investigated. On the basis of principal component analysis and optimization of spectral regions, regression models for qualitative and quantitative detection of adulteration among the set of investigated oils were built. These results were additionally confirmed by gas chromatography. In the second part possibilities for monitoring oxidative stability of oils with FT-IR were examined in a set of commercially important edible oils (the previously mentioned set extended by palm and hazelnut oil). By using the standard Rancimat method oxidative stability indices in the temperature range from 130 to 160 °C were determined for these oils and the results were confirmed by FT-IR. Application of FT-IR method has multiple advantages over the standard Rancimat method because FT-IR is a non-destructive, cheap, fast and mobile technique with no necessary chemical pretreatment of oil samples. In addition, FT-IR could monitor the progress of formation of some secondary oxidation products depending on the temperature and time of oxidative degradation.