Simple chlorination enables efficient degradation of refractory N-containing phosphonates.

N‑containing phosphonates are extensively utilized in industrial applications, primarily owing to their high chelating capacity towards metal ions. However, conventional degradation approaches for these compounds are frequently hampered by low treatment efficiency and high operational costs. In this work, we present chlorination as a simple yet robust strategy for the oxidative decomposition of various N‑containing phosphonates. Taking diethylenetriaminepenta(methylenephosphonic) acid (DTPMP) as a representative substrate, our experimental results reveal that chlorination achieves rapid and nearly quantitative conversion to orthophosphate, with an efficiency of 95.5% obtained within 5 min under the optimal pH of 7. Mechanistic investigations indicate that HClO, identified as the predominant reactive chlorine species, serves as an electrophile that preferentially targets the electron‑rich central N atom of DTPMP, thereby triggering CN bond scission and subsequent orthophosphate liberation. This inherent reactivity endows the chlorination system with remarkable tolerance to coexisting water constituents and enables satisfactory performance in real water matrices, thereby resulting in a lower operational expenditure compared with the UV/peroxydisulfate system. Furthermore, the chlorination process is capable of efficiently degrading transition metal-phosphonate complexes. This study offers a simple, energy‑saving, and cost‑effective alternative for the remediation of N‑containing phosphonate contamination in wastewater.