Cilj: Utvrditi razliku u antioksidativnoj aktivnosti maslinovog, suncokretovog, bučinog i crnog ulja i njihovih tokoferolnih ekstrakata te proučiti kinetiku i mehanizam reakcije između slobodnih radikala i antioksidansa. Materijali i metode: Antioksidativna aktivnost ulja i tokoferolnih ekstrakata mjerena je spektrofotometrijski uz uporabu DPPH˙ (2,2-difenil-1-pikril-hidrazil), dok je Trolox ekvivalent poslužio kao referentni standard za kvantifikaciju rezultata dobivenih DPPH˙ testom. Pomoću kinetičkih monofaznih i bifaznih matematičkih modela procijenjena je i analizirana inhibicija signala DPPH˙. Rezultati: Vrijednost TEAC-a ukazuje da maslinovo i suncokretovo ulje (2,16 mmol/L) posjeduju jaču antioksidativnu aktivnost u odnosu na crno (1,85 mmol/L) i bučino ulje (1,68 mmol/L), a ujedno i intenzivniju inhibiciju DPPH˙ radikala. Tokoferolni ekstrakti imaju puno slabiji antioksidativni učinak od analiziranih biljnih ulja, pri čemu je najdjelotvorniji ekstrakt suncokretova ulja koji čini 22,1 % antioksidativne aktivnosti ulja, a najslabiji ekstrakt bučina ulja sa samo 13,9 %. Nestanak DPPH˙ radikala u uzorcima ulja odvija se u dva susljedna koraka, početnog eksponencijalnog koji se odvija unutar 7 min reakcije, ovisno o vrsti ulja, i drugog sporog, gdje su promjene proporcionalne s vremenom. Kod tokoferolnih ekstrakata brzi korak reakcije nije uočen, ukazujući time da se reakcija odvija mehanizmom kinetike prvog reda. Zaključak: Rezultati ukazuju da biljna ulja imaju jači učinak u inhibiciji radikala u odnosu na tokoferolne ekstrakte, pa se njihovom pravilnom konzumacijom potpomaže organizmu u „borbi“ protiv slobodnih radikala. Zapravo, najvažniji dio antioksidacijskog sustava obrane organizma od slobodnih radikala čini sinergističko djelovanje antioksidansa, odnosno antioksidansi u sinergiji imaju jači učinak nego sumarni učinak svih pojedinačnih antioksidansa. Aim: To determine the difference in the antioxidant activity of the olive, sunflower, pumpkin and black oil and their tocopherol extracts as well as to examine the kinetics and mechanism of reactions between free radicals and antioxidants. Materials and Methods: Antioxidant activity of the oils and tocopherol extracts was measured spectrophotometrically using DPPH˙ (2,2-diphenyl-1-picrylhydrazil) while Trolox equivalent was used as a reference standard for the quantification of the results obtained by the DPPH˙ test. DPPH˙ signal inhibition was evaluated and analyzed by monophasic and biphasic kinetics mathematical models. Results: The TEAC values suggest that olive and sunflower oil (2.16 mmol/L) have a stronger antioxidant activity than black (1.85 mmol/L) and pumpkin oil (1.68 mmol/L) and they possess stronger inhibition of the DPPH˙ radical. Tocopherol extracts have a much weaker antioxidant effect than the analyzed vegetable oils, where the sunflower extract is most effective, making 22.1 % of the antioxidant oil activity, while the weakest extract is the pumpkin oil extract oil with only 13.9 %. DPPH˙ radical disappearance in oil samples takes place in two successive phases, the initial exponential which takes place within 7 min of the reaction, depending on the oil type, and the second slow phase where the changes are proportional to the time. The rapid reaction phase by tocopherol extracts was not noticed, indicating that the reaction takes places by the mechanism of the first order kinetics. Conclusion: The results indicate that vegetable oils have a stronger effect on the radical inhibition than the tocopherol extracts, and by their proper consumption they will support the organism in the “fight” against free radicals. In addition, the most important role of the antioxidant defense system against free radicals makes the synergic interactions among the different molecules present in the food, indicating that antioxidants in synergy have a stronger potential than the sum of all individual antioxidants.