By means of 57Fe Mössbauer effect, distribution of hydrogen and its interaction with iron in stainless steel and Fe-Ni alloys are studied. Paramagnetic single line spectrum of hydrogenated stainless steel is analyzed into two components. One arises from the iron atoms totally unaffected by hydrogen and the other from those largely affected by hydrogen. A large positive isomer shift of the latter can not be explained by the lattice expansion but by the increase in the number of 3d electrons of iron due to the interaction with hydrogen. Ferromagnetic six line spectra of hydrogenated Fe-Ni alloys also consist of two parts, one being from the γ' phase, in which iron atoms have little interaction with hydrogen because of its inhomogeneous distribution, and the other from the hydride like β phase, in which the iron atoms inevitably interact with nearby hydrogen atoms and their magnetic moment is reduced by 15%. This experiment shows non-uniform distribution of infused hydrogen in iron alloys and, at the same time, remarkable effects of the electronic interaction between hydrogen and iron. Disagreements in the past experiments are well interpreted from the above results and point of view