Three hesperetin Schiff bases: hesperetin thiosemicarbazone (HTSC), hesperetin isoniazone (HIN) and hesperetin benzhydrazone (HHSB) have been synthesized and characterized by using analytical and spectral techniques. The influence of substituents on hesperetin antioxidant activity has been studied in vitro using mitochondrial assays. The studied compounds have been found to exhibit both antioxidant and pro-oxidant activity