We report the photocatalytic activity of uniform-sized nanocrystalline mesoporous titania synthesized via surfactant-mediated hydrothermal method. All the prepared catalysts were systematically characterized by various analytical, spectroscopic and imaging techniques. The characterization results indicate that all the catalysts under investigation possess uniform-sized nanocrystalline particles having mesoporous pore structure with narrow pore size distribution. The phase transformation occurs from anatase, brookite to rutile phase while increasing the calcination temperature. The performance of mixed phase titania for the photocatalytic degradation of 4-chlorophenol was analyzed. These catalysts show much higher activity than commercial titania (Aeroxide; P-25) owing to synergistic effect of stable mesoporous structure and mixed crystalline phases of titania.