As a dietary component, flavonoids are thought to have a variety of pharmacological and health‐promoting properties in both in vivo and in vitro systems. This variety is attributed to their high antioxidant capacity, which in turn is associated with their free radical scavenging properties. In order to understand the mechanism of t‐BuO• radical scavenging properties of some flavonoids, viz, quercetin (QU), apigenin (AP), daidzein (DA), genistein (GE), myricetin (MY), and kaempferol (KA), a kinetic study of photo‐oxidation of these flavonoids with photochemically generated t‐BuO• radicals in a t‐BuOH water (2:1 v/v) system was carried out. The oxidation of flavonoids by t‐BuO• radicals was performed spectrophotometrically by measuring the absorbance of quercetin (375 nm), apigenin (340 nm), daidzein (250 nm), genistein (263 nm), myricetin (255 nm), and kaempferol (375 nm) at their respective λmax. The initial rates of oxidation of flavonoids increased with [flavonoid], [t‐BuOOH], and light intensity. The quantum yields (φ) were considered from the initial rate of oxidation of flavonoids by t‐BuO• radicals and measured light intensity at 254 nm. The order on [flavonoid] and [t‐BuOOH] was found to be fractional, whereas the order on light intensity was found to be one. The products of the oxidation of flavonoids by t‐BuO• radicals were identified using LC–MS and FTIR analysis.