Combined hard x-ray photoelectron spectroscopy (HAXPES) and electrical characterisation measurements on identical Si based metal-oxide-semiconductor structures have been performed. The results obtained indicate that surface potential changes at the Si/SiO2 interface due to the presence of a thin Al or Ni gate layer can be detected with HAXPES. Changes in the Si/SiO 2 band bending at zero gate voltage and the flat band voltage for the case of Al and Ni gate layers derived from the silicon core levels shifts observed in the HAXPES spectra are in agreement with values derived from capacitance-voltage measurements. © 2012 American Institute of Physics.