A theoretical model equation has been derived to relate the growth kinetics of silicide coating with the pack chemical composition and other processing conditions for siliconizing of Mo-TZM (Mo-0.5Ti-0.1Zr-0.02C) alloy to improve its oxidation resistance at high temperatures. A series of experiments conducted with varying pack Si (1-10 wt %) and NH4F (2-20 wt %) content, time (1-25 h), and temperature (800-1200 degrees C) confirmed the validity of the model. MoSi2 was the main coating layer formed during the siliconizing process. Optimum processing conditions were derived for doping of Al in MoSi2 to form Mo(Si,Al)(2) in the outer layer of the coating. (C) 2008 The Electrochemical Society. [DOI: 10.1149/1.2987954] All rights reserved.