To recycle elemental molybdenum from waste molybdenum disilicide (MoSi₂) heating elements, the MoSi₂ was first disintegrated to MoO₃ and SiO₂ powders in air at a pest oxidation temperature of 500 °C. X-ray diffraction (XRD) patterns confirmed the completion of the pest oxidation reaction. The mixture of MoO₃ and SiO₂ powders were heated to 950 °C in a tube furnace to evaporate MoO₃, and the XRD patterns of the residue showed that only SiO₂ was left in the crucible, confirming that the MoO₃ was removed through thermal evaporation. The collected MoO₃ crystals had a striped morphology. Photocatalytic performance of MoO₃ showed superior activity in comparison with commercial MoO₃ and P25 for the degradation of methylene blue under visible light irradiation. The photocatalytic degradation activity of MoO₃ synthesized by thermal evaporation at 950 °C was 99.25% in 60 min.