Abscisic Acid (ABA) is a water stress hormone that signals stomatal closure at the pico mol concentration level. In order to enhance detection sensitivity and understand stomatal responses to ABA biosynthesis and catabolism, we are applying a chemical procedure for molecule recognition, ‘molecular imprinting'. The principal behind the procedure is the formation of a polymer complex around a specific target molecule. Once formed, the complex contains cavities with binding sites that are complementary to the shape and size of the target molecule. In addition to the high specificity, molecular imprinting technology is non-invasive and dynamic (environmentally inert and thermal and pH stable). Currently, we have developed a molecular imprint that binds ABA. Using UV spectrophotometry, ABA has been detected in a series of in vitro experiments. The next phase of our work will focus on refining the detection system with fluorescence/chemiluminescence. The molecular imprinting tool will then be used to quantify and characterize the hormonal water stress response from the cellular to the ecosystem level.