The luminescence behaviour of n-type gallium phosphide (100) was studied during electrochemical pore etching in HF and HBr electrolytes. Strong visible oscillating light emission is observed that is correlated with current oscillations during the electrochemical etching process. The intensity of the electroluminescence strongly depends on the etchant and there is an increase of two orders of magnitude in intensity by using a HBr instead of HF electrolyte. Therefore, we conclude direct coupling between electron transfer at the semiconductor-electrolyte interface and the light emission mechanism. (c) 2005 Elsevier B.V. All rights reserved.