Abstract— The reaction of tetrakis‐(dimethylamino)‐ethylene (I) with oxygen in non‐hydroxylic solvents gives tetramethylurea (II), tetramethyloxamide (III), tetramethyl‐hydrazine (IV), and bis‐(dimethylamino)‐methane (V) in yields that are virtually independent of solvent and temperature, or whether chemiluminescence occurs. Autoxidation over water solutions, however, first gives octamethyloxamidinium peroxide (VI) which then hydrolyzes to give III and dimethylamine, and undergoes an alternative demethylation reaction to give tetramethyl 2‐(dimethylamino)‐2‐hydroxy‐2‐(methylamino)‐acetamidinium (VIII) and formate (IX) salts. Both courses of autoxidation are observed in solutions containing lithium chloride, in methanol or in water‐dioxane mixtures. A common intermediate is suggested.