The redox behavior of a gold electrode in an ammoniacal electrolyte (0.1 M NH3 and 0.1 M NaClO4) was investigated using four techniques. These were the rotating ring disk electrode (RRDE), the electrochemical quartz crystal microbalance (EQCM), X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectrometry (TOF-SIMS). Two different gold surface compounds, AuO and AuNH2, are formed in relative amounts that depend on the holding time at +0.6 V (versus SCE). XPS and SIMS studies were used to distinguish the surface species AuO and AuNH2 from AuO and AuOHNH2. When the potential is held at +0.6 V for longer times, other oxidized gold surface species may form, e.g. AuO, AuOHNH2, [OHO(NH2)Au](2)NH, AuNH2, Au2O3. 2NH(3) and Au2O3. 3NH(3). During the gold electrode oxidation process, NH3 is probably oxidized to N-2. During the surface gold species reduction process, some soluble Au(III) species form that can be reduced to an adsorbed Au(I) species at -0.4 V.