The capacity of a photocatalyst system to degrade water pollutants was optimized using solar-light-sensitive TiO2 and the swelling behavior of a hydrogel TiO2 synthesized via a sal-gel process was modified by multielement doping to change its solar-light-responsive properties A hydrogel was used for the rapid absorption of both anionic and cationic water pollutants. TiO2 particles were immobilized in/on hydrogel fibers by an electrospinning method for the easy recovery of TiO2, and the ability of the hydrogel/TiO2 composite to degrade dye molecules was studied The TiO2 particles were observed to have maintained their original anatase-type crystallinity in/on the electrospun hydrogel fibers The dye degradation capacity of the hydrogel/TiO2 composite was investigated using both anionic and cationic dyes under sunlight Two mechanisms were suggested by which the hydrogel/TiO2 composite can remove dye particles from the water. (1) the absorption of dyes by the hydrogel and (2) the degradation of the dye by the TiO2 in the hydrogel Both of these mechanisms were investigated in this study We found that the dye was effectively absorbed by the hydrogel fibers as demonstrated by the swelling behavior of the hydrogel and the nano-size effects. The dye was then introduced to the TiO2 particles for degradation (C) 2010 Elsevier Inc All rights reserved