An electro-catalyst for the oxidation of ammonia in alkaline media; the electrocatalyst being a noble metal co-deposited on a support with one or more other metals that are active to ammonia oxidation. In some embodiments, the support is platinum, gold, tantalum, or iridium. In some embodiments, the support has a layer of Raney metal deposited thereon prior to the deposition of the catalyst. Also provided are electrodes having the electro-catalyst deposited thereon, ammonia electrolytic cells, ammonia fuel cells, ammonia sensors, and a method for removing ammonia contaminants from a contaminated effluent.