Molybdenum oxide, MoO3, is a promising cathode material for high energy density lithium batteries. We report measurement of transport properties of lithium-intercalated MoO3 using electrical resistivity, Hall effect, electrochemical titration and far-infrared spectroscopy. Both electronic and ionic conductivities are measured for reversible lithium intercalation of MoO3. Electronic conductivity is characteristic of a metal. The ionic conductivity increases with Li concentration to 1. 5 X 10(-4) S cm-1 in Li0.7MoO3. Li+ diffusivity in LixMoO3 is high, reaching a maximum of 10(-9) cm2 s-1. The charge transfer mechanism is discussed.