Ni-Fe-P alloys were electrodeposited in Watts' type nickel baths containing ferrous chloride and phosphonic acids. The Ni and P content of the alloys increased with increasing current density or increasing phosphonic acid concentration, whereas the Fe content decreased with increasing P content. The X-ray diffraction intensity of the alloys was progressively lowered by increasing the P content. Alloys containing more than 8.0% P were substantially amorphous. It seems that plating baths of low Ni²⁺ concentration are preferable for obtaining amorphous Ni-Fe-P alloys. The anodic polarization curves for electrodeposited amorphous Ni-Fe-P alloys in 0.1N sulfuric acid did not exhibit passivity, but the alloys were much more highly corrosion resistant than crystalline Ni-Fe alloys.