The effects of roasting temperature and time on color, crude oil, acrylamide, total phenols, antioxidant activity, and trans fatty acid and phenolic contents in white and brown sesame seeds. Samples were roasted in a microwave oven (360, 540, 720 W; 5, 10, 15 min) and an electric oven (180°C, 200°C, 220°C; 10, 20, 30 min). Phenolic and antioxidant contents changed significantly. Maximum total phenolic content and antioxidant activity values were noted for samples roasted in the electric oven at 220°C for 30 min (white, 264.17 mg/100 g, 74.76%; brown, 289.79 mg/100 g, 74.32%, respectively). Dominant fatty acids did not change significantly following electric oven roasting. Roasting at 200 and 220°C caused trans fatty acid formation. Elaidic and linolelaidic acid contents were 0.05%–0.36%, 0.06%–0.33% in white sesame and 0.22%–0.41%, 0.06%–0.23% in brown sesame, respectively. Acrylamide formation was not detected. Practical applications: Sesame oil obtained from roasted sesame seeds, is rich in unsaturated fatty acids, has a long shelf life and a unique aroma. Roasting process successfully increase oil, antioxidants, and total phenol content of sesame seeds. After processing of sesame seeds, major phenolic compounds were altered. Roasting of sesame seeds at 220°C using conventional method is more suitable than other methods. Trans fatty acids (elaidic and linolelaidic) formation was observed at high temperatures.