A laser operating at 266 nm was used to photolyze the product of the ClO+NO2+M reaction, and the yield of Cl atoms, measured by resonance fluorescence, was found to be identical to that from equivalent concentrations of ClONO2, strongly suggesting that no other isomers are formed in the recombination reaction. Evidence for isomers is reviewed, and the apparent forward-and-reverse-rate constant discrepancy explained as a probable uncertainty in the thermochemistry.