The neutralization of chemical warfare agents (CWAs) continues to be a pressing area of interest for the safe and effective removal of these hazardous compounds. Among the various CWAs, the most nefarious are organophosphate nerve agents (such as sarin), which contain P=O, P-O-C, and P-C bonds that enable lethal phosphorylating mechanisms. Over the past few decades, a variety of destruction and neutralization methods have been used to safely eliminate these hazardous compounds. For example, destruction-based methods (typically pyrolysis) allow a one-step approach for the complete disposal of CWAs at the expense of using specialized equipment under extreme conditions. On the other hand, neutralization methods offer potentially reversible chemical treatments, leading to possible CWA precursors under less severe conditions. Recent studies have shown that metal oxides can effectively destroy CWAs due to their high surface area, a large number of highly reactive edges, corner defect sites, unusual lattice planes, and high surface-to-volume ratios. In particular, metal oxides, such as CaO, MgO, ZnO, TiO 2 , Al 2 O 3 , Fe 3 O 4 , and CuO 22 are candidates as adsorbents for enhancing the decomposition of CWAs. In γ-Al 2 O 3 , Al atoms in the bulk exhibit either a tetrahedral or octahedral coordination. However, depending on the exposed crystallographic surface, Al atoms on the surface can display penta-, tetra, and tri-coordination and exhibit Lewis acidity. Because of its high degree of surface heterogeneity, γ-Al 2 O 3 offers a high catalytic activity and is a promising candidate for the decomposition of various CWAs. In this work, we present the first ab initio molecular dynamics study for probing hightemperature decomposition dynamics of diisopropyl methylphosphonate (DIMP) on the γ-Al 2 O 3 surface. Due to its structural similarity with sarin, DIMP has been used in experiments to mimic the decomposition reaction mechanism of CWAs. DIMP is the only surrogate with the same isopropyl (-O-C 3 H 7 ) group found in sarin gas (the only structural difference between sarin and DIMP is the substitution of a fluorine for an isopropyl group in the former). Several techniques have also been used to probe DIMP decomposition, including microwave discharge approaches, pyrolysis on porous substrates, laser heating, and thermal decomposition at 700 -800 K. Despite these experimental studies, theoretical analyses of DIMP decomposition on metal oxides are scarce, except for a previous study on mechanism and rates of thermal decomposition of DIMP. In this work, we utilize largescale ab initio molecular dynamics simulations to probe the adsorption dynamics and time scales of DIMP decomposition at various temperatures. In addition, we present new ab initio-based metadynamics simulations to calculate free-energy barriers for various bond breaking decomposition reactions of DIMP. These computational techniques allow us to (1) predict activation energies and detailed mechanistic pathways at various temperatures and (2) establish accurate sarin decomposition models on metal-oxide surfaces to guide experimental efforts for neutralizing DIMP.