The efficient detection, decontamination, and destruction of chemical warfare (CW) agents remain an active area of scientific research. Rate constants for the reaction of substituted diethyl phosphates and phosphonates with the hydroxyl radical and hydrated electron have been measured in water to elucidate the primary destruction pathway for the CW agents Tabun (GA), Sarin (GB), Soman (GD), and VX with these two species. The measured kinetics for simulants with leaving groups that more closely mimic these actual CW agents predict that reductive destruction will be the most efficient mechanism, and that nontoxic simulants such as alkyl phosphonates undergo different redox chemistry.