Background: There are great interests in photocatalytic oxidation of contaminants using titanium dioxide in recent years. The main objective of this research was to study photocatalytic disinfection of Coliform bacteria as water microbial pollution index using TiO2 and a low pressure UV lamp in a batch reactor. Methods: The polluted water was prepared by adding a colony of Coliform in raw water and in separate stages was contacted with UV, TiO2 and combination of them and various parameters such as contact time, pH and amount of TiO2 were studied in terms of their effect on reaction progress. Results: The results showed that in simultaneous presence of both UV ray and TiO2, there was the most effective disinfection of Coliform. This study showed that 100% of Coliform was killed by irradiation for 60-75 min. in the presence of 0.8 gr l-1 TiO2 in pH=7.0. Conclusion: Based on the results, UV/TiO2 process may be effectively applied for disinfection of polluted water and can be suggested as a effective purifying method for water disinfection.