The electro-oxidation of azide ions on gold and platinum electrodes in aqueous neutral media was investigated using cyclic voltammetry. Gold in the presence of azide ions undergoes electro-oxidation forming gold azide complexes above +0.1 V vs. Hg/Hg2SO4. Anodic oxidation of azide ions produces gaseous products at potentials above +0.5 V vs. Hg/Hg2SO4. The formation of gold azide complexes by azide electro-oxidation at gold has been reported for the first time. On the other hand, azide ions undergo electro-oxidation at platinum electrodes and yield directly gaseous products at potentials above +0.5 V vs. Hg/Hg2SO4. This difference in the reaction mechanisms of the azide ion electro-oxidation between gold and platinum electrodes is confirmed using electron spectroscopy for chemical analysis measurements and rotating ring-disk experiments. A reaction mechanism is discussed for the electro-oxidation of the azide ions at the gold surface.