Silica gels that controlled the pore size were prepared by calcination of silica/organic polymer (50/50 wt %) composites prepared by the sol-gel process. Poly(ethylene oxide) (PEO)-poly(propyrene oxide) (PPO)-PEO triblock copolymers, which are called poloxamers, were used as an organic polymer. The pore control of the silica gels was carried out by changing the molecular weight of PEO or PPO in the poloxamers. The silica gels obtained by the above procedure had a dual pore size of around 4 nm and below 2 nm in diameter, and the specific surface area was 500-1000 m(2)/g. The poloxamer molecules were supposed to be dispersed monomolecularly in the composites. Therefore, the pore structure of the silica gels reflected the structure of the poloxamer and, particularly, the radius of gyration of PPO in the composites.