An Si-gate metal-oxide-semiconductor (MOS),electron tunneling cathode was fabricated and its emission characteristics were examined. The emission OCCUrred at a gate voltage higher than the work function of the Si gate by electron tunneling through the potential barrier in the MOS cathode and was stable in the Si-gate cathode. The energy distribution of emitted electrons was measured and was confirmed to be mainly determined by the scattering process of hot electrons in the oxide. The emission current from the Si-gate MOS cathode was nearly independent of pressure.