A bifunctional gas-diffusion electrode operative alternately for gas consumption and gas evolution comprises a gas-side layer in which gas consumption takes place, an electrolyte-side layer where gas evolution takes place and an intermediate rectifying layer of semi-conducting material arranged between the gas-side layer and the electrolyte-side layer so as to prevent unwanted gas evolution in the gas-side layer. The rectifying layer may be a p-n junction or may form part of a Schottky barrier junction.