A design of experiments approach was employed to study the coalescence of combustion-sprayed ethylene-methacrylic acid copolymer (EMAA), The powder feed rate, stand-off distance, substrate temperature, propane flow rate, and compressed air flow rate were studied by using a 2(5-1) factorial design matrix. Empirical models were developed to predict coating surface roughness, coating temperature and splat elongation ratio. Such methods allow process optimization, estimation of interactions among parameters, and the determination of the factors which influence the coalescence of ethylene-methacrylic acid copolymer coatings.