The primary events of the oxidative transformation of quinoline, an environmental pollutant, by different radicals have been investigated using pulse radiolysis. The hydroxyl radical reacts by adding to both pyridine and benzene rings of quinoline to form the OH-adducts. On the other hand, SO4(.-) oxidizes the quinoline to its radical cation, which further undergoes hydrolysis to yield the OH-adducts. The possibility of the quinoline radical cation to undergo hydrolysis has been independently verified by generating the radical cation under laser induced photoionization conditions. The quinoline radical cation produced in acetonitrile shows high reactivity toward water. The rate for (OH)-O-. reaction is greater (k = 1.0 x 10(10) M-1 s(-1)) than that found for SO4.- reaction (k = 3.5 x 10(9) M-1 s(-1)). With oxidation potential at 1.87 V vs NHE, quinoline is nonreactive toward N-.(3) radicals and less reactive toward O-.(-) radicals (k = 3.2 x 10(8) M-1 s(-1)). The mechanistic understanding of the primary oxidation pathway of quinoline will aid in designing strategies for the abatement of pollutants containing nitrogen heterocycles.