α-MoO₃ nanobelts were successfully prepared by a facile hydrothermal method with sodium molybdate (Na₂MoO₄) as the Mo source and NaCl as the capping agent. The as-prepared products were characterized using Fourier transformation infrared spectrophotometry (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electronic diffraction (SAED) and their pseudocapacitive properties were investigated in a 0.5 M aqueous Li₂SO₄ solution by cyclic voltammetry (CV), chronopotentiometry (CP) and AC impendence. The results show that the dimensions of the as-prepared α-MoO₃ nanobelts are 200–400 nm in width, ca. 60 nm in thickness and 3–8 µm in length. The redox potential for the α-MoO₃ nanobelts is found in the range of −0.3 to −1.0 V vs. SCE, which indicates that the α-MoO₃ nanobelts can be used as anode electrode materials for hybrid supercapacitors. The specific capacitances of the α-MoO₃ nanobelts at 0.1, 0.25, 0.5 and 1 A g⁻¹ are 369, 326, 256 and 207 F g⁻¹, respectively. The maximum specific capacitance of the α-MoO₃ nanobelts is much higher than those of MoO₃ nanoplates with 280 F g⁻¹, MoO₃ nanowires with 110 F g⁻¹ and MoO₃ nanorods with 30 F g⁻¹ recently reported in literature. Furthermore, the α-MoO₃ nanobelt electrode exhibits a good cycle stability with more than 95% of the initial specific capacitance maintained after 500 cycles. Additionally, the present route to prepare nanostructured MoO₃ is much less expensive than those with Mo powders as the Mo source. Overall, the obtained high performance α-MoO₃ nanobelts could be a promising electrode material for supercapacitors.