Various shapes and sizes, including spherical, cubic nanoparticles and hexagonal nanorods with the dimensions of 50-500nm, of TiO2 were prepared through hydrolysis of titanium butoxide in sol-gel method with the introduction of different surfactant composition and concentrations during preparation. Prepared TiO2 nanoparticles were studied for photocatalytic decomposition of methyl orange (MO) in fixed film batch reactors. The results showed that shape, size and photocatalytic activity of TiO2 depend not only on surfactant composition but also on surfactant concentration. Photocatalytic decomposition of MO followed the first order kinetic reaction. The analysis of reaction rate constants showed that the shape is more important than the size in determining the photocatalytic activity of shape- and size-controlled TiO2 nanoparticles. TiO2 nanorods had higher photocatalytic activities than spherical and cubic TiO2 nanoparticles.