It has been revealed that the oxide layer which covers ZnSe is removed by very simple hydrogen (H,) gas treatments. The H, gas was clacked by a tungsten heater set in a ceramic tube. The apparatus of the gas irradiation is inserted into the growth chamber of MBE through a K-cell port. The RHEED patterns of oxidized ZnSe surfaces show drastic change from spotty to streaky ones after exposure to the clacked H, gas. The photoluminescence spectra of the H, treated ZnSe indicate (A(0), x), SA- and Cu-green-like structures. The temperature of the substrate was kept at 340 degreesC during the H-2 treatment, which is the growth temperature of MBE-ZnSe.