Surface chemical and electronic properties of electroplated Rh/Si(111)-interfaces were investigated by cyclovoltammetry, HRTEM, electrochemical impedance and synchrotron radiation photoelectron spectroscopy (SRPES). The strong adsorption of hydrogen onto (photo)-electrochemical deposited Rh crystallites brings about a source of atomic hydrogen, which diffuses into the silicon substrate. The incorporation of hydrogen turns the underlying substrate amorphous and passivates dopant energy states. This inverts the conduction type of the semiconductor with the formation of an apparent surface pn-junction which controls the electronic behavior of the metal/semiconductor contact. (C) 2014 The Electrochemical Society. All rights reserved.