Molybdenum Coating was sprayed on 45 steel substrate using novel electrothermal explosion directional spray. Microstructure and composition of the coating were analyzed with SEM and EDS, respectively. Hardness of the coating was tested by hardness testing machine. Grain sizes of Mo coating were measured. It shows that the grain of molybdenum coating is very fine. The maximum hardness of the coating is up to HV=1411, 3 times of the sprayed molybdenum material. The coating is dense and the porosity is little. EDS shows that oxidation do not occur during the spraying process.