After September 11, 2001 terrorist attacks, Congress considered proposals to regulate industrial security (The Republican, 2006). Especially, organophosphates are frequently used in agriculture as pesticides, insecticides, herbicides, and fungicides. In addition, organophosphates comprise several classes of chemical warfare agents. Dimethyl methylphosphonate (DMMP) is used extensively as a type G and X nerve agent simulant due to its similar structure and solubility properties to toxic organophosphonates. This study attempts to exploit the greater inherent nucleophilicity of NaX than NaY, due to a lower Si-Al ratio in NaX, in order to decompose DMMP within zeolite supercages. Our initial effort was to identify the degradation products in the NaX. Then the impact of water on DMMP decomposition was also studied by systematically varying the loading of water and/or DMMP. The ultimate goal was to optimize the decomposition of DMMP.