The electro‐oxidation and adsorption of ammonia in aqueous alkaline solution on a platinized platinum electrode has been investigated by using the potentiodynamic technique. For comparison, the oxidation of hydroxylamine as well as potassium nitrite was also studied. It was concluded that the primary step of ammonia oxidation involves one electron. The primary product was relatively stable, indicating that the rate‐determining step is one of the later steps of the net reaction. Pavela's method was used in conjunction with the potentiodynamic technique to study the adsorption of ammonia. The adsorption was found to be in accord with Temkin's isotherm, and the surface coverage of adsorbed ammonia was found to be about 0.3 at saturation.