Abstract. Using electronic absorption spectra and thin layer chromatography, the reaction of 2,2-diphenyl-1-picrylhydrazyl (DPPH) with O2•–, HO•, HO– , and HOO– anions and free radicals revealed the formation of the para-nitro- and para-hydroxy-derivatives of 2,2-diphenyl-1-picrylhydrazine (DPPH2) and of DPPH fragmentation products (diphenylamine, tetraphenylhydrazine). The reaction of DPPH with the O2•– anion-radical (from KO2 in benzene