In this work, we have harnessed large-scale ab initio molecular dynamics calculations to investigate the adsorption and decomposition of DIMP on the γ-alumina surface over a wide range of temperatures. Our DFT-based molecular dynamics calculations predict a spontaneous decomposition of DIMP with propene as the main by-product within the 700 -1000 • C temperature range (the decomposition reaction leads to propene and an Al-OCHCH 3 CH 3 adsorbate at 700 • C). Due to the short-time scales inherent to BOMD simulations, it is likely that a similar decomposition would also occur at lower temperatures but would take longer to happen. Well-tempered metadynamics AIMD simulations were performed for temperatures ranging from 200 -1000 • C to provide atomistic-level details of the reaction path and associated energetics of DIMP decomposition. Our metadynamics calculations also reveal that the free energy barrier value decreases with temperature. The low free energy barrier values at higher temperatures suggest that that reaction is extremely fast at higher temperatures and is likely to occur at a lower rate at lower temperatures.