The ethene-ozone reaction was investigated in a 570 L spherical glass reactor at atmospheric pressure, using long-path FTIR spectroscopy for detection of the individual products. Experiments were performed in the presence of hydroxy and carbonyl compounds to identify the reactions of the Criegee intermediate CH2OO formed in ethene ozonolysis. Using C-13-labeled HCHO, this reaction was found to proceed via an unstable cyclic adduct which decays to the detected products HCHO, HCOOH and CO. [CH2OO + HCHO --> HCHO + HCOOH (eq 13); CH2OO + HCHO --> HCHO + CO + H2O (eq 14a); CH2OO + HCHO --> HCHO + HCO + OH (eq 14b)] The relative rates of the reactions of CH2OO with HCOOH and HCHO were determined from the product analysis. In addition, evidence was found that the reaction of CH3CHO with the CH2OO intermediate does not exclusively produce secondary propene ozonide, but also HCHO and CO2. The results of this study have been combined with data from previous investigations to give a complete description of the gas phase ozonolysis of ethene and are discussed in comparison with ozonolysis reactions occurring in the liquid phase.