This paper reported the electrodeposition of the nickel manganese alloy coatings from a sulphate bath using sodium citrate as complexing agent. The cyclic voltammetric experiments showed that the alloy initiative codeposition potential was about –0.457 V (vs.SCE). The effect of the plating conditions on the composition and the structure of the Ni-Mn were studied by energy dispersive X-ray spectrum and X-ray diffractometer, respectively. As a result, with the increase of the cathodic current density from 10 to 40 mA·cm-2, the manganese content of the deposit increased from 4.4 at% to 10.3 at%, and then it slightly decreased. The phase structure of the coating was face centered lattice (Fm3m) Ni-Mn solid solution. The corrosive polarization experiments indicated that the deposit could work as sacrificial coating for carbon steel in 3.5 wt% sodium chloride solution.