Alumina-Titania coatings were obtained by detonation gun thermal spray process on ferritic steels namely T11 (1Cr 0.5 Mo steel ASTM-SA213-T-11) and T22 (2.25 Cr 1 Mo steel ASTM-SA 213-T-22) and were evaluated for their performance inside the running boiler of a thermal power plant. In D-gun process, particle velocity is extremely high which may be effective in increased interlocking between particles and thus highest possible density. Homogeneous and dense coatings performed well and were found to provide adequate protection to the substrate steels. Copyright © 2009, Inderscience Publishers.