In this research, ZnO coatings were deposited on stainless steel substrate by flame spraying (FS) and air plasma spraying (APS) processes. Phase analysis and microstructure of coatings were evaluated by X-ray diffractometry (XRD) and scanning electron microscopy (SEM), respectively. UV-VIS-NIR spectrophotometer was used for evaluation of light absorption. Degradation of methylene blue solution method was used for evaluation of photocatalytic activity of coatings. The results showed that thermal spray processes increase the light absorption and decrease the band gap of ZnO, The results indicated that these characteristics are the main factor in photocatalytic subjects. The results showed that flame spray process is not an appropriate process for applying photocatalytic coating for aqueous solutions. On the other hand, photocatalytic activity of coatings which were produced by air plasma spraying are more appropriate process in this regard. Among the APS coatings, the best photocatalytic activity and reaction rate constant were related to sample with the highest roughness, porosity and light absorption. The results indicated that the reaction rate of methylene blue degradation by ZnO thermal spray coating is followed by a first-order kinetics process. Furthermore, Light intensity can have a strong effect on photocatalytic activity of ZnO coating. Keywords Zinc oxide, Photocatalyst, Flame spray, Air plasma spray, Methylene blue, Photocatalytic activity.