Numerical predictions and experimental observations have been correlated to improve the qualitative understanding of the degree of thermal degradation occurring during the HVOF spray deposition of nylon-11. Particle residence time (similar to 1 ms) in the HVOF jet was insufficient for significant decomposition of the nylon-11, but was sufficient for noticeable discoloration (yellowing) of the particles of a powder with a mean particle size of 30 mu m. Experimental observation showed this to be the case even though numerical predictions indicated that the temperature of a 30 mu m diameter particle should be considerably higher than the upper degradation limit of nylon-11. Initial thermal oxidation of nylon-11 promotes the formation of carbon-carbon double bonds that strongly absorb in the visible spectrum even at concentrations of parts per million causing discoloration of the nylon. (c) 2007 Wiley Periodicals, Inc.