Abstract This paper reports a study on the photolysis of an aryl pentazole in solution. 4- Oxidophenylpentazole (OPP) was irradiated in water and in acetonitrile at its first absorption band (320 and 370 nm, respectively) and at 193 nm. 4-Oxidophenylazide (OPA) was also investigated under similar conditions for comparison. NMR and UV–vis absorption spectroscopies of the products show that the major stable products of OPP photolysis in ...