Heat‐treatment was shown to increase the rate of corrosion of Zr‐2Sn‐2Nb over that of the annealed condition, but the rate of hydrogen pickup as a function of total corrosion was found to be relatively insensitive to heat treatment. The effects of heat treatment have been analyzed in terms of changes in: (i) alloy constitution, (ii) composition of microconstituents, and (iii) the metal texture and oxide orientation. Stereoscopic examination of oxide‐film surfaces by electron microscopy revealed cracking both at grain boundaries and at interfaces between phases. Extensive and abrupt changes in film topography, which also were sites of film cracking, were observed.