The influence of anodic contact glow discharge electrolysis on a Pt auxiliary electrode in alkaline electrolyte was investigated as a function of the distance between the electrodes and time. By studying the electrochemical properties of Pt before, during and after aCGDE by cyclic voltammetry, we demonstrate that the Pt auxiliary electrode can be used to monitor operando the formation of H 2 O 2 by aCGDE in the electrolyte. The concentration depends on the distance of the electrodes to each other and the detection time.