The electronic switching properties of thioacetamide dimer (TAD) were investigated using the nonequilibrium Green's function method combined with density functional theory for design of a novel molecular switch. The H‐bonded TAD can be converted upon hole‐trapping to a three‐electron (3e)‐bonded configuration with a S∴S linkage which could provide a more favorable channel for charge transfer than the before. The redox‐induced configuration conversion between the H‐bonded and the 3e‐bonded TADs could govern the charge migration through the molecular junction with a considerable difference in conduction currents. The calculated I–V characteristic curves of two configurations exhibit a switching behavior with an On‐Off ratio in a range of about 4.3–7.6 within the applied voltages. Clearly, this hypothetical scheme provides a potential way to explore the novel conformation‐dependent molecular switch. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010