The redox behaviour of copper species in an 'ammonium imide' room temperature molten salt was examined to clarify the applicability of the salt to the electroplating media of various metals. Trimethyl-n-hexylammonium bis((trifluoromethyl)sulfonyl)amide (TMHA-Tf2N), having an electrochemical window of 5.6 V (50 degreesC), and the corresponding copper(II); salt were used to prepare the solution. In TMHA-Tf2N media the monovalent copper ion, Cu(I), was stable and Cu metal was oxidized, or corroded, in the presence of Cu(II) species as: Cu2+ + Cu-->2Cu(+). Cathodic electrodeposition of copper metal and its anodic dissolution were, thus one-electron reactions and their current efficiencies were almost 100%.