Erosion may be defined as the destruction of a material by abrasive action of a liquid or gas. The wearing away is purely mechanical with no electro-chemical reaction. This process occurs on surfaces, pipelines wherever the flow of liquid along with particles in suspension causes erosion. In this investigation, the erosion rate on a coated surface was studied using pot erosion tester. The substrate material used was stainless steel of grade 316. The material was machined to the required dimensions and was coated one set with tungsten carbide- cobalt and another set with alumina. The coating was done using a detonation spray process. The specimens were weighed before and after the testing. The mass loss and erosion wear rate were calculated. It was found that the erosion wear rate was minimum when the speed of rotation was 3 m/ sec and increases as the speed increases. The SEM examination revealed the formation of flake type debris due to the interaction between the erodent and the specimen.