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This work reports the transduction of the reaction of the enzyme acetylcholinesterase (AChE) with acetylcholine (AC%) as a model to demonstrate how transient electrochemical signals from bilayer lipid membranes can be obtained by appropriate selection of the lipid composition of membranes. Membranes were prepared from mixtures of egg phosphatidyl choline (PC) and dipahnitoyl phosphatidic acid (DPPA) for this purpose. Hydronium ions generated by the enaymatic reaction at the surface of BLMs caused a transient current due to a dynamic alteration of the electrostatic fields at the surface of such membranes. The results were consistent with an electrostatic mechanism of perturbation of the surface structure of the BLMs, where changes of local hydronium ion activity which were associated with the enzymatic reaction altered the extent of ionization of the headgroups of the DPPA, thereby providing a transient charging current which lasted for a period on the order of seconds. The delay time for observation of the transient was directly and reproducibly related to the concentration of the substrate, which could be determined over a range of +I to mM levels. Investigation of the effects of solution pH, the presence of Ca'+ and the use of the enzyme inhibitor Neostigmine confirmed that the response was due to a genuine selective chemical transduction process.