VX is a representative nerve agent and its rapid detoxification relays on the development of catalysts and understanding of the mechanism on an atomic level. Herein, we report that a Lindqvist-type [Nb6O19](8) (Nb-6) can effectively catalyze the detoxification of VX simulant, OSDEMP. Within 5 min OSDEMP can be completely converted to the minimally toxic product in the presence of H2O2. Various experimental evidences: (1) negligible conversion of DMNP (an organophosphorus ester without S center); (2) effect of solvent polarity; (3) O-18-labeled experiment confirm that the detoxification of OSDEMP by Nb-6 follows an oxidation pathway. Further experimental and theoretical studies (e.g. spectroscopic analysis, control experiments, kinetic studies, and DFT calculations, etc.) reveal that Nb(eta(1)-OOH) hexaniobate is the dominant active species and both the formation of Nb(eta(1)-OOH) hexaniobate species and oxygen transfer process are rate-determining steps. The proposed mechanism can also be applied to the catalytic oxidation of sulfur mustard simulant. (C) 2021 Elsevier Inc. All rights reserved.