Herein, the delta phase bismuth oxide (delta-Bi2O3) with high crystallinity can be obtained at room temperature through a sol-gel route in the presence of VO3 (-). The as-synthesized delta-Bi2O3 photocatalysts are characterized using synchrotron-based techniques, including ultraviolet photoelectron spectroscopy, X-ray absorption near edge structure, and extended X-ray absorption fine structure. Results show that V species plays a key role in stabilizing the delta phase of Bi2O3. With increasing V/Bi molar ratio, crystallinity, light absorption ability, and specific surface area increase. The V species predominantly exists in the +5 oxidation state, irrespective of V loading amount, and is tetrahedrally coordinated to four O atoms with a bond length of 1.716 a"<<. The delta-Bi2O3 photocatalysts show appreciable visible light activity for the decomposition of atenolol, an important beta-blocker drug.