Degradation of perfluorooctanoic acid (PFOA) is of great importance due to its global distribution, persistence and toxicity to bioorganisms. In present study, a composite TiO 2 with multiple wall carbon nano-tubes (MWCNTs) was synthesized using sol–gel method and it was used as photocatalyst to degrade PFOA in water. The prepared composite catalyst displayed significant absorption in UV to visible light region. The loading content of TiO 2 on MWCNTs could be adjusted by changing the ratio of precursor to MWCNTs. Due to the combined effect of the adsorption ability and e − transport capacity of MWCNT, the composites displayed much higher photocatalytic ability to PFOA as compared to pure TiO 2 under UV irradiation. The photocatalyst prepared with 10:1 of tetrabutyl titanate/MWCNT was the most effective. With the optimal dosage at 1.6gL −1 , almost 100% of PFOA was degraded in acid medium after irradiation for 8h. It was proposed that PFOA were mainly degraded by stepwise losing a moiety of CF 2 .