Cellulose acetate butyrate/TiO2 hybrid membranes were prepared via phase inversion by dispersing the TiO2 nanoparticles in casting solutions. The influence of TiO2 nanoparticles on the morphology and performance of membranes was investigated. The scanning electron microscope images and experiments of membrane performance showed that the membrane thickness and pure water flux were first increased by adding the TiO2 nanoparticles to the casting solution up to 4 wt% and then decreased with the addition of further nanoparticles to it. The obtained results indicated that the addition of TiO2 in the casting solution enhanced the rejection and permeate flux in filtration of bovine serum albumin solution. Furthermore, increasing the TiO2 nanoparticle concentration in the casting solution increased the flux recovery and consequently decreased the fouling of membrane.