This study was carried out to prepare functional cookies using sour orange peels powder and nano-particle sour orange peels as a rich source of phytochemicals. The phytochemicals in wheat flour, sour orange peels powder, nano-particle sour orange peels and the produced cookies were determined, and polyphenols compounds in sour orange peels and nano-particle sour orange peels were identified by HPLC. Also, the chemical composition of wheat flour, sour orange peels powder and the prepared cookies were carried out. Whereas physical properties, color measurements and sensory evaluation were determined in wheat flour cookies and sour orange peels powder cookies. The results showed that sour orange peels cookies contained the highest ash content. The nano-particle sour orange peels had the highest total phenolic content, total flavonoid content and antioxidant activity being 9.05 mg GAE / g, 2.10 mg QE / g and 90.13 %, respectively. The addition of sour orange peels powder to wheat flour up to 7.5 % was accepted by the panelists. From the results, it could be indicated that the nano peels particles are a good source of phytochemicals and minerals which improves the quality of cookies. Therefore, it could be recommended that using sour orange peels up to 7.5% enhanced the antioxidant properties and nutritional value of the prepared cookies.