The photocatalytic degradation of n-pentane in gas phase has been investigated under different conditions on a TiO2 DEGUSSA P25 at room temperature, in dry air, in a flow through reactor. Several parameters have been studied such as the concentration of n-pentane [25-500]ppmv for a total flow of 120mL/min, the molar flow rate (0.10-2.5mmol/min), and the modulation of the irradiance at 365nm. The degradation and the mineralization into CO2 were followed through a gas analysis with a GC/FID/Catalytic Methanizer. Preliminary results showed that a complete mineralization of n-pentane into CO2 seems to be always achieved whatever the operating conditions. Moreover, the degradation rate of n-pentane reached about 0.05mmol/min. This work shows also that the a conversion rate of 44% is reached for a molar flow rate of 0.10mmol/min.