The O-3-molecule initiated degradation of three 2-alkenals (E)-2-heptenal, (E)-2-octenal, and (E)-2-nonenal has been investigated in a 1080 L quartz-glass environmental chamber at 298 +/- 2 K and atmospheric pressure of synthetic air using in situ FTIR spectroscopy to monitor the reactants and products. The experiments were performed in the absence of an OH scavenger. The molar yields of the primary products formed were glyoxal (49 +/- 4) % and pentanal (34 +/- 3) % from the reaction of (E)-2-heptenal with 03, glyoxal (41 +/- 3) % and hexanal (39 +/- 3) % from the reaction of (E)-2-octenal with O-3, and glyoxal (45 +/- 3) % and heptanal (46 +/- 3) % from the reaction of (E)-2-nonenal with O-3. The residual bands in the infrared product spectra for each of the studied reactions are attributed to 2-oxoaldehyde compounds. Based on the observed products, a general mechanism for the ozonolysis reaction of long chain unsaturated aldehydes is proposed, and the results are compared with the available literature data.