A novel transparent conductive film In2O3:Mo (IMO) was sputtered onto a Si wafer, and the energy band alignment at the IMO/Si interface was studied. A large built-in potential (Vd = 1.77 eV) was detected by capacitance–voltage (C–V) measurement, and the schematic band alignment of IMO/p-Si was plotted. The conduction and valence band offsets have been deduced as ΔEc = 0.86 eV and ΔEv = 1.62 eV, respectively. The current–voltage (I–V) measurements show rectifying characteristic for IMO/p-Si and ohmic contact for IMO/n-Si. Reverse current–temperature (I0–T) measurements gave an activation energy Eac = 0.23 eV, which represents the transition from the top energy level in a narrow and deep well to the conduction band of IMO. The measurement of a photocurrent spectrum showed signals of three discrete levels in the narrow potential well, and the energy value of the transition from the top level to IMO (0.17–0.23 eV) agrees well with the Eac obtained by the I0–T measurement.