A convenient and green method for the oxidation of nitrogen-rich heterocyclic amines to nitro-substituted heteroaromatics using potassium peroxymonosulfate (2KHSO 5 •KHSO 4 •K 2 SO 4 , Oxone) in water was developed. This method has several advantages over previous methods: operational simplicity, safety, inexpensive reagents, the use of H 2 O as the sole solvent, and mild conditions. The utility of the present oxidative system was demonstrated by the synthesis of the important energetic compounds 3,4,5-trinitro-1H-pyrazole (TNP) and 5-amino-3-nitro-1H-1,2,4-triazole (ANTA).