The main objective of this work was to examine the feasibility of coupling electrochemical and biological processes to destroy nitrate ions (NO 3 − ) while producing biohydrogen. In this integrated process NO 3 − was firstly converted to ammonium using an electrochemical flow cell. After only one pass of concentrated nitrate solutions (3gNO 3 − L −1 ) through the flow cell, ammonium ions selectivity of 98.8%, corresponding to 0.86gNH 4 + L −1 was recorded. The obtained ammonium solution was then tested as a nitrogen source to produce H 2 in a batch system involving heat-treated aerobic activated sludge.In the optimal conditions corresponding to pH 5.5 and initial glucose concentration of 15gL −1 , consumption yields were 97% and 82% for ammonium and glucose, leading to H 2 yield of 0.35molH 2 mol −1 glucose consumed. The H 2 production was associated with acetic/butyric acids type fermentation. Obtained biogas contains only H 2 and CO 2 and was free of methane, hydrogen sulphide, and nitrous oxide. Therefore, the targeted objectives were achieved since on the one hand selective and quantitative conversion of NO 3 − to NH 4 + was shown and on the other hand the obtained NH 4 + was completely assimilated by activated sludge with the production of biohydrogen, a clean energy carrier.