Organophosphates (OPs) are a synthetic class of compounds used in a variety of functions ranging from mild pesticides to potent nerve agents. These compounds inhibit acetylcholinesterases, resulting in toxicity to a wide range of animals, including humans. Several phosphotriesterases have been reported in the literature to hydrolyze and detoxify these agents. We have globally replaced phenylalanine with para-fluoro-phenylalanine into a phosphotriesterase from Pseudomonas diminuta. The enzyme bearing the fluorinated amino acid is shown to have an enhanced thermostability as compared to the wild-type enzyme, potentially making this a useful for bioremediation application.