6,8-Diazaflavin (1) and 6,8-diaza-7-methylthioflavin (2) show remarkablyhighoxidizing activity towards thiols and nitroalkanes; 6,8-diazaflavins [(1) and (2)] are 106–108 times more reactive in the oxidation of thiols compared with 3,10-dimethylisoalloxazine.