Mo/W oxide hollow microspheres with MoO₃ as matrix material were fabricated via a polyethylene glycol (PEG) induced aqueous route. The hierarchical Mo/W oxide samples are constructed by elementary fusiform particles, which were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) methods. Initial formed h-WO₃ crystallites acted as nuclei for subsequent formation of MoO₃ precipitates, thus Mo/W oxide samples formed through epitaxial growth strategy show weak crystallization because of the lattice mismatch between h-MoO₃ and h-WO₃ crystals. The MoO₃ based Mo/W oxide samples exhibit good photochromic performances compared to unitary h-MoO₃ and h-WO₃ crystals.