Autoxidation of linoleic acid was carried out in the temperature range from 323 K to 343 K using a bubble column reactor. A slow initial increase in hydroperoxide at low concentration range of hydroperoxide (induction period) and a rapid increases in hydroperoxide at high concentration of hydroperoxide after a certain time (acceleration period) were observed during the reaction. The experimental results are analyzed by the radical chain reaction model proposed. The rate equation of hydroperoxide formation with two apparent kinetic constants is developed to explain the autoxidation rate of linoleic acid. Effects of UV irradiation in the presence or absence of TiO2 powder are also studied. Autoxidation of linoleic acid was accelerated by UV irradiation and especially by the photocatalytic effect of TiO2. A remarkable acceleration effect by UV and photocatalysis of TiO2 is observed in the induction period and these effects are enhanced at lower temperature.