The purpose of this study was to determine the influence of seed roasting temperature on chemical composition of pumpkin seed oil. Pumpkin seeds were roasted at temperatures from 90 to 200 °C, one sample was left unrosted as control. In pumpkin seed oil samples five polycyclic aromatic hydrocarbons (PAHs) were determined by high performance liquid chromatography. The PAHs started to form at 150 °C and their concentrations increased with the increase of temperature. Volatile aroma compounds were also determined by means of solid phase microextraction (SPME), followed by gas chromatography. Aldehydes and alcohols prevailed at low roasting temperatures, while higher temperatures caused the formation of pyrazines, which resemble a roasted-like aroma. The concentrations of α- and γ-tocopherol did not change significantly with the increase of temperature, whereas polyphenol concentrations did change. At the beginning of roasting they increased and decreased as the temperature increased further. Antiradical activity was determined via 2,2-diphenyl-1-picrylhidrazyl (DPPH) method, its values were increasing till 110 °C and decreased afterwards. To verify the geographical origin, pumpkin seed samples from different countries were collected and analysed on fatty acid and sterol composition by gas chromatography as well as on stable isotope ratios by mass spectrometry. On the basis of these results and combination with chemometrics we were able to distinguish even the samples from neighbouring countries (Slovenia, Austria, Croatia). These analyses were also used to determine the botanical authenticity. For this purpose rapeseed, sunflower and soybean oil were added to pumpkin seed oil in varying ratios (1-10 %(w/w). The results confirmed that the combination of fatty acid profiles and δ13C values, combined with chemometrics, gave 100% correct classification even when only 1 % of foreign oil was added.