The hydrogen distribution in the oxidized Zircaloy-2 was related to its microsturcuture by tritium microautoradiography based on a cathodic tritium charging method. It was found out that hydrogen atoms were concentrated in the intermetallic precipitates such as Zr(Fe,Cr)2 and Zr2(Fe,Ni) existing in the oxide film, and on the grain boundary of zirconium matrix. It was also found out that hydrogen atoms were scarcely present in the thin metallic region adjacent to the oxide layer, the thickness of which was about 10–15 µm.