In order to elucidate photo-fading mechanisms of azomethine dyes which are used to form color photographic images, photo-fading products of degassed solutions of model yellow dye YD1 or YD2-carbonyl compounds-alcohols were identified. YD1 is 1-phenyl-2-(4-diethylamino-phenyl)-iminobutane-1, 3-dione and YD2 is 1, 3-dipheny1-2-(4-diethylamino-phenyl)-imino-propane-1, 3-dione. To identify the products, two kinds of trials were made. The first kind of the trials was identification of the photo-fading products after separation and purification by column and thin layer chromatography in ordinary atomospheric condition and it was confirmed that the products had changed from a compound to other various ones and the direct identification was impossible. However two kinds of α-diketone type compounds were identified, one of which lacked a benzoyl group and another of which lacked an acetyl group. On the second kind of the trials throughout in a degassed system, identification of the photo-fading products had gone on smoothly because the identical reactions proceeded and the identical compounds were produced from the initial to the last stage of fading of solutions, and it was confirmed from NMR and mass spectra that the products were leuco forms of the dyes. Moreover it was confirmed that in solution the leuco form of YD1 existed as isomeric equilibrium at least, one isomer was keto form and another was enol form. However the leuco form of YD2 existed only as keto form.