Photo-oxidation reactions in a mixture of C2H6/O-2/CO2 are investigated with KrF excimer laser irradiation. The main initial products are acetaldehyde and ethanol. The reaction is induced by one-photon absorption of O-2 which yields to O-2(A＇ (3)Delta(u)). It is considered that C2H6 reacts principally with O-2(A＇) to generate oxidation products. The solvent density effects on the light absorption process of O-2 and its subsequent quenching processes are discussed.