Orthorhombic molybdenum trioxide (α-MoO3) is a layered oxide with promising performance as electrode material for Li-ion capacitors. In this study, we show that expansion of the interlayer spacing (by ~0.32Å) of the structure along the b-axis, introduced by partial reduction of α-MoO3 and formation of MoO3−x (x=0.06–0.43), results in enhanced diffusion of Li ions. Binder-free hybrid electrodes made of MoO3−x nanobelts and carbon nanotubes show excellent electrical conductivity. The combination of increased interlayer spacing and enhanced electron transport leads to high gravimetric and volumetric capacitances of about 420F/g or F/cm3 and excellent cycle life of binder-free MoO3−x electrodes.