TiO2 photocatalyst Degussa P25 was modified by three methods: SO42-acidification (labeled as STH), SO42- acidification combined with microwave irradiation (labeled as STW), and microwave irradiation (labeled as WT), respectively. FT-IR and XRD were used to characterize the structural properties of these TiO2 samples, whereas surface photovoltage spectroscopy (SPS) provided important information on the photoelectric properties. The photo-oxidation of gaseous cyclohexane over P25, STH, STW and WT was monitored by in-situ infrared technology. The experimental results demonstrated that the modified TiO2 samples were more active than the original P25 and followed this order: WT > STW > STH > P25. During the photocatalytic oxidation of cyclohexane over WT, cyclohexane was mineralized into carbon dioxide and water. Moreover, CO was also produced in small amount. (C) 2009 Elsevier B.V. All rights reserved.