Reactions of coadsorbed t-butoxy and NO, generated by thermal dissociation of t-butyl nitrite dosed onto Cu(111), were investigated using time-of-flight mass spectrometry, temperature-programmed desorption, and Auger electron spectroscopy. In the high-temperature regime above 500 K, t-butyl alcohol, isobutene, carbon oxides, and molecular nitrogen desorb. In the more complex regime below 500 K, nitrous oxide, molecular nitrogen, hydrazine, water, carbon oxides, and acetylene desorb. The proposed low-temperature reaction pathways involve rearrangement of adsorbed nitric oxide to form N2O and N-2, reaction between adsorbed (CH3)(3)CO(a) and O-(a) or N-(a) to form a metallocyclic intermediate (1) and either adsorbed O(a)H or N(a)H. The intermediate (1) undergoes multiple C-C bond cleavages in a series of steps to form carbon oxides and adsorbed methylenes. The latter couple to form di-sigma-bonded ethylene, which can either dehydrogenate to acetylene or be partially oxidized to acetate that dissociates in the high-temperature region. The proposed high-temperature t-butoxy decomposition is a bimolecular reaction involving transfer of hydrogen without forming chemisorbed H on Cu.