Abstract The major route of degradation of tetrazepam (1) is oxidation to 7-chloro-5-(3-keto- cyclohexen-1-yl)-1, 3-dihydro-1-methyl-2H-1, 4-benzodiazepin-2-one (3) via the stable 7- chloro-5-(3-hydroperoxycyclohexen-1-yl)-1, 3-dihydro-1-methyl-2H-1, 4 benzodiazepin-2- one (2). Minor degradation products are 7-chloro-5-(1, 2-epoxycyclohexan-1-yl)-1, 3-dihydro- 1-methyl-2H-1, 4-benzodiazepin-2-one (5) and 7-chloro-1, 3-dihydro-1-methyl-2H-1, 4- ...