TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The hydroxylic acid is selected from glycolic acid, lactic acid, malic acid, tartaric acid and citric acid.    TECHNOLOGY FOCUS - POLYMERS - Preferred Process: The water in the aqueous solution is brought to a subcritical water state by hydrothermal synthesis, ultrasonic irradiation or microwave irradiation of the aqueous solution. The molar ratio of the template and fine particles in the aqueous solution comprising the mixture of the template and fine particles is (not greater than 20, preferably not greater than 10) for the fine particles with respect to 1 for the template. The process further involves adding a molecule with a functional group that attracts at each other the template by hydrophobic interaction and a functional group that attracts at each other the fine particles by electrostatic attraction, to the aqueous solution comprising the mixture of the template and fine particles. Preferred Components: An amphiphilic poly(alkylene oxide) block copolymer is used as the template, where the poly(alkylene oxide) block copolymer has a molecular weight of not less than 1000 and contains hydrophilic poly(alkylene oxide) (preferably poly(ethylene oxide)) in an amount of 30 - 60%. The block copolymer comprises at least one block copolymer selected from triblock copolymer having hydrophilic poly(alkylene oxide) covalently bonded to the opposed ends of hydrophobic poly(alkylene oxide), and diblock copolymer having hydrophobic poly(alkylene oxide) covalently bonded to the end terminal of hydrophilic poly(alkylene oxide). The hydrophobic poly(alkylene oxide) is selected from poly(propylene oxide), poly(butylene oxide), poly(phenylene oxide) and polyhydroxylic acid (preferably polyhydroxylic acid). EXAMPLE - Poly(ethylene oxide)-poly(propylene oxide)- Poly(ethylene oxide) (triblock copolymer) of formula ((EO)20-(PO)70-(EO)20) was used as the template, while Ce oxide with a particle size of about 4 nm and exhibiting an oxygen occluding/releasing function was used as the fine particles. The fine particles were dispersed in purified water, and hydrochloric acid was added to the dispersion to a pH of below 1. Next, EO20-PO70-EO20 was added to this dispersion at a pH of below 1, and then more fine particles were added while stirring to obtain an aqueous solution comprising a mixture of the template and fine particles. The weight ratio of the water, (EO)20-(PO)70-(EO)20 and fine particles was 120:4:1. After thorough mixing, the aqueous solution was transferred to a pressure-resistant vessel and subjected to hydrothermal synthesis treatment at 180degreesC for 24 hours, as subcritical water treatment. The aqueous solution was then returned to room temperature, atmospheric pressure, tetraethyl orthosilicate was added to the aqueous solution to a weight ratio of 2:1 with respect to the template, and hydrothermal synthesis was repeated at 100degreesC for 24 hours in the pressure-resistant vessel to obtain a precipitate. The precipitate was removed from the pressure-resistant vessel and dried, and then fired at 600degreesC to burn off the template, to obtain a mesoporous structure comprising fine particles made of Ce oxide with a particle size of about 4 nm, situated in the pores of a mesoporous body made of silica.