We studied chemiluminescence spectroscopy to develop an evaluation method for organic material degradation. The thermal oxidation of oleic acid as a monounsaturated fatty acid was investigated using chemiluminescence measurements. The obtained spectra indicated that the luminescence consisted of several peaks, including peaks for singlet oxygen and excited carbonyls. A detailed analysis of the nuclear magnetic resonance and infrared absorption spectra allowed us to determine the probable structures of the oxidative products. The relationship between the spectrum and the analyzed structure implied that the wavelength of the carbonyl group emission peak shifted as a result of the structure. (C) 2013 Elsevier B. V. All rights reserved.