To investigate the interaction between molecules incorporated into hydrogels and gel framework of hydrogels, SiO2 and TiO2 hydrogels containing a surfactant or Ru(bPY)(3)(2+) are prepared by a sol-gel method. For the hydrogels into which a surfactant is incorporated, the interaction is investigated through aggregation behavior of the surfactant. When the surfactant has no charge or the same charge as that of gel framework, the interaction is weak and aggregation of the surfactant occurs. When Ru(bpy)(3)(2+) is incorporated, it is absorbed strongly by SiO2 gel framework but not absorbed by TiO2 one. The interaction between Ru(bpy)(3)(2+) and SiO2 gel framework is so strong as to change photochemical properties of Ru(bPY)(3)(2+) greatly.