Bi 2 S 3 nanorods in flower-shaped bundles were successfully synthesized from the decomposition of Bi–thiourea complexes under the microwave-assisted hydrothermal process. X-ray powder diffraction (XRD) patterns and field emission scanning electron microscopy (FE-SEM) show that Bi 2 S 3 has the orthorhombic phase and appears as nanorods in flower-shaped bundles. A transmission electron microscopic (TEM) study reveals the independent single Bi 2 S 3 nanorods with their growth along the [001] direction. A possible formation mechanism of Bi 2 S 3 nanorods in flower-shaped bundles is also proposed and discussed. Their UV–vis spectrum shows the absorbance at 596nm, with its direct energy band gap of 1.82eV.