摘要： Titanium dioxide (TiO2) is among the most potential photocatalyst. However, TiO2 only works under UV light due to the relatively wide band gap energy. To overcome this, TiO2 is infiltrated (doped) by rare earth elements such as gadolinium (Gd). TiO2 was synthesized using sol gel method, while Gd/TiO2 photocatalyst was synthesized by the mixing methods of sol-gel and impregnation. The crystals are then characterized using XRD and SEM-EDX. The XRD diffractogram demonstrated that the crystallinity synthesized of TiO2 had an anatase structure similar to the structure of anatase P-25 as references. The SEM-EDX showed that Gd ion could not enter the crystal lattice, but only dispersed on the surface of TiO2 particles. The optimum result of decreased Cr(VI) concentration was reported using Gd/TiO2 1% w/w by a decrease of up to 94%, after irradiated with ultraviolet for one hour.