The current paper deals with the corrosion behaviour of permanent magnetic alloy, SmCo5 in two different environments like marine and industrial environments. The results show that the corrosion rate of the alloy becomes almost doubled in industrial environments when compared to marine environments. The studies also revealed that the alloy could not form protective oxide scale on its surface in both the environments studied. The alloy was found to be vulnerable to corrosion in both marine and industrial environments. Scanning electron microscope results indicate that the magnetic alloy undergoes pitting type of corrosion in marine environment and intergranular corrosion in industrial environments. The sequences of steps that reduce its magnetic properties under corrosive atmospheres have been proposed. Based on the results, the importance of surface engineering techniques in exploitation of the magnet, SmCo5 for a variety of applications by improving the corrosion resistance under marine and industrial environments has been highlighted.