Dye-sensitized TiO2 and platinum ion-doped TiO2 photocatalysts were synthesized and their physicochemical characteristics and visible light reactivities were investigated. When ruthenium complexes were used as a sensitizer of TiO2, the visible light induced degradation of perchlorocompounds could be achieved through a reductive path. However, the sensitized TiO2 is not stable enough to be a practical photocatalyst. In a related sensitized TiO2 system, a simultaneousremoval of dyes and heavy metal ions was observed in visible light illuminated TiO2 suspensions and the removal rate of each component was synergistically enhanced. The electron injection from an excited dye into the conduction band of TiO2 and the subsequent reduction of metal ions on TiO2 take place concurrently to exhibit a novel synergic effect. This model system of ternary components (dye/ TiO2/metal ion) can be a basis of solar remediation technology for dye-contaminated wastewaters. On the other hand, platinum ion doped TiO2 as a visible light photocatalyst was synthesized and characterized to demonstrate its successful performance in degrading recalcitrant organic pollutants.