The side streams derived from the palm oil production process, namely palm kernel cake, palm pressed fibre, palm kernel shells and empty fruit bunches, were evaluated as sources of phenolic compounds. Among these streams, kernel cake had the highest total phenolic content (in mg of gallic acid equivalents (GAE) per g of dry sample) with a value of 5.19, whereas the empty fruit bunches had the lowest value (1.79). The extraction time and liquid-to-solid ratio were investigated to optimize the phenolic extraction. Kernel cake exhibited the highest total phenolic content (5.35 mg/g) with a liquid-to-solid ratio of 40:1 during 20 min of extraction. The main phenolic compounds of the extracts deriving from all byproduct streams were also identified and quantified with HPLC-DAD. Pyrogallol, 4-hydroxybenzoic acid, gallic acid and ferulic acid were the main compounds found in kernel cake extracts. Empty fruit bunch and pressed fibre extracts were also rich in 4-hydroxybenzoic acid, while pyrogallol was the predominant compound in kernel shell extracts. All extracts showed antioxidant activity as it was indicated from the results of DPPH analysis and subsequently tested in sunflower oil aiming to prolong its shelf life. The addition of 0.8 % kernel cake extract increased the induction time of sunflower oil more than 50 %. According to the results obtained in this study, kernel cake extracts could be considered as a value-added co-product with a potential application as antioxidants in the food industry.; Nusproizvodi proizvodnje palminog ulja, i to pogača od palminih sjemenki, palmina vlakna, ljuske palminih sjemenki i prazni grozdovi palminog ploda, upotrijebljeni su za ekstrakciju polifenolnih spojeva. Među tim nusproizvodima je pogača od palminih sjemenki sadržavala najviše ukupnih fenolnih spojeva, i to 5,19 mg u g suhe tvari, izraženih kao ekvivalent galne kiseline, dok je najmanje imao prazni grozd palminog ploda, i to 1,79 mg/g. Radi optimiranja ekstrakcije fenola ispitani su sljedeći parametri: vrijeme ekstrakcije i omjer tekuće i krute tvari. Najveći ukupni udjel fenola od 5,35 mg/g pri omjeru tekuće i krute tvari od 40:1 tijekom ekstrakcije od 20 min imala je pogača od palminih sjemenki. Pomoću HPLC-DAD metode određeni su glavni fenolni spojevi iz nusprodukata proizvodnje palminog ulja. Pogača od palminih sjemenki sadržavala je najviše pirogalola, te 4-hidroksibenzojeve, galne i ferulinske kiseline. Prazni grozdovi palminog ploda i palmina vlakna bili su bogati hidroksibenzojevom kiselinom, dok je pirogalol bio dominantan sastojak ekstrakta ljuski palminih sjemenki. Svi su ekstrakti imali oksidacijsku aktivnost, koja je potvrđena DPPH analizom, te ispitana dodatkom ekstrakta suncokretovom ulju radi produljenja roka trajanja. Dodatkom 0,8 % ekstrakta pogače od palminih sjemenki povećalo se indukcijsko vrijeme suncokretovog ulja za više od 50 %. Rezultati istraživanja potvrđuju da je pogača od palminih sjemenki nusproizvod s dodanom vrijednošću koji se može upotrijebiti kao antioksidans u prehrambenoj industriji.