Laser surface alloying of Ni-Co electroplated steel using 900 W CW CO2 laser to develop Fe-Ni-Co alloy on the surface is reported. Fe-Ni-Co alloys of different compositions are produced by varying the working speed from 0.25 m/min to 3m/min and laser spot size from 0.6 mm to 5mm. The development of microstructure in the melted zone is analysed in terms of composition variation and cooling rate. The microhardness of newly formed alloys reported here are three times higher as compared to base metal. Martensite is observed in the laser modified zone.