Use of poly(ethylene oxide)-b-poly(propylene oxide) (PEO-b-PPO) diblock copolymers with appropriate block ratios effectively increases the structural period of the mesoporous silica films with a two-dimensional hexagonal structure, which are prepared by the evaporation-induced self-assembly process. The number of the hydrophobic PPO block can control the periodicity over a wide range, which reaches even ca. 20 nm.