First, catalyst variation and solvent optimization studies are reported for polyoxoanion-supported transition-metal precatalysts, novel complexes such as [(1,5-COD)Ir I·P 2W 15Nb 3O 62] 8−, [(C 6H 6)Ru II·P 2W 15Nb 3O 62] 7− and [(OC) 3Re I·P 2W 15Nb 3O 62] 8−, catalyzing cyclohexene oxidation at low (≤25%) conversion with O 2 to, predominatly, four main autoxidation products: 2-cyclohexen-1-yl hydroperoxide, 2-cyclohexen-1-one, 2-cyclohexen-1-ol, and cyclohexene oxide, all at a mass balance of ≥80–92% under the low conversion conditions. Next, radical-chain initiator, inhibitor, and other kinetic (rate law) evidence for the reaction behaving, at lower conversions, as classical Haber–Weiss autoxidation was obtained. Those studies lead, in turn, to the study of cyclohexene autoxidation at higher conversions, notably the identification of ca. 70 gas chromatography (GC)-detectable products. This was followed by identification of 27 of those ca. 70 products, the first reported detailed identification of more than 8–10 products of cyclohexene autoxidation. These results led, in turn, to the five main findings of this study: (i) product and kinetic—overall compelling—evidence that the main reaction is free-radical-chain autoxidation; (ii) the first detection of ca. 70 cyclohexene autoxidation products, followed by the identification of 27 of those products—this is not trivial given that complete product studies are the required first step of rigorous mechanistic work; (iii) plausible arrow-pushing mechanisms to many of the observed products using known radical chemistry—previously unavailable schemes; (iv) the observation of chlorinated hydrocarbons among the products, results which require the precedented participation in the oxidation catalysis by CH 2Cl 2 solvent-derived, CHCl 2 radicals, and perhaps most significantly (v) the development of a relatively simple and quick, yet definitive, GC and GC–MS fingerprint method for detecting autoxidation catalysis using the prototype olefin, cyclohexene. Such product studies should prove to be a useful tool in the continuing problem of detecting, or ruling out, classical autoxidation in attempts to develop new oxidation chemistry using O 2 as a highly desirable terminal oxidant.