© 2020, Turkish Chemical Society. All rights reserved.In this study, numerous coumarin compounds were synthesized by Pechmann and Knoevenagel methods, and the substitution of the formyl group was provided by the Duff reaction. The FTIR spectra and melting points of the synthesized compounds were compared with the literature values. The structures were also confirmed by GC/MS analysis. Besides, the synthesized coumarin derivatives were compared in terms of antioxidant activity according to DPPH and CUPRAC methods. The main aim of the study is to determine the effects of substituents on antioxidant activity.