The selective reduction of NO2- to N-2 in 0.1 M NaOH was obtained at a Pt(100) electrode in a narrow but distinct potential region. This is the first report of such selectivity for this reaction on Pt(100), which is known to be the most catalytically active platinum surface toward NO2- reduction in alkaline media. Both ammonia and nitrous oxide are ruled out as possible reaction intermediates on the basis of online electrochemical mass spectrometry. Based on earlier work on ammonia oxidation, NH2 adsorbates are speculated to be involved in the reaction mechanism.