Photocatalytic degradation of N-methyl-2-pyrrolidone (NMP) was investigated in an aerated UV/TiO2 batch system. The effects of TiO2 photocatalyst loading, temperature, pH, initial concentration, and the type of gas phase on the reaction rate were ascertained, and the optimum conditions for the maximum degradation rate were determined. The results showed that photocatalytic degradation of NMP is strongly influenced by these parameters. The optimum TiO2 loading, which provides enough surface area for reaction without irradiation loss due to scattering of UV light, was found to be 0.1 wt %. It was revealed that due to bilateral effect of temperature on the process, the maximum oxidation rate (0.22 min(-1)) is obtained at 45 degrees C. The highest photodegradation reaction rate is obtained in neutral or slightly acidic condition rather than in extreme acidic or alkaline range. The pseudo-first-order reaction rate expression based on Langmuir-Hinshelwood model can reasonably simulate the photocatalytic degradation process. The optimum values for TiO2 photocatalyst loading, temperature, and pH were confirmed by economic factor analysis based on electrical energy consumption.