Amorphous iron‐zirconium alloys, ranging in composition from to , have been studied by anodic polarization and passivation decay in 1N sulfuric acid. The results showed a compositional enhancement of corrosion resistance with increasing zirconium concentration. Auger electron spectroscopy indicated that exposure to the sulfuric acid solution enhances the surface zirconium concentration with respect to the bulk of the exposed alloy and also with respect to the as‐deposited surface composition. X‐ray photoemission spectroscopy shows that the passive film is a mixture of zirconium oxides and hydroxides and iron oxides and hydroxides.