Manganese-copper alloys were pulse plated from a sulfate solution with the addition of ammonium sulfate at pH 6.7. An electrochemical investigation of the Mn-Cu electrodeposition system was conducted by potentiodynamic methods. The effect of pulse-plating on cathodic efficiency, microstructure, and crystallography of the deposits was analyzed and compared with the results from continuous plating. Pulse plated coatings with short off-time were characterized by an uniform and homogeneous morphology, suitable mechanical properties, and low copper content (< 5 wt %). The codeposition of copper prevented the phase transformation of as-deposited ductile gamma-Mn to the brittle and hard alpha-Mn. All the coatings exhibited a good sacrificial protection for steel in sulfate and chloride media. (c) 2006 The Electrochemical Society.