Electrolyte/metal interface is interesting as the place of producing material because we can control the process dynamics by means of applied potential to metal. In this paper, we electrodeposited CdTe thin films on Au(111)/polyethylene in 50mM H₂SO₄+1mM CdSO₄+0.1mM TeO₂ aqueous solution. The electrodeposited thin films were investigated by X-ray Photoelectron Spectroscopy (XPS), Electro-Chemical Atomic Force Microscopy (EC-AFM) and electrochemical measurement. The film electrodeposited at-1000mV (vs. Hg/Hg₂SO₄) consisted mainly of CdTe compound and was much less oxidizable than Cd film and Te film. Based on the result of in-situ EC-AFM measurement, we ascertained the CdTe deposition mechanism under this condition.