The catalytic effects on the crosslinking behavior of poly(ethylene-co-vinyl trimethoxysilane) were investigated for three different catalysts: the commonly used tin-based compound dibutyltin dilaurate (DBTDL), a low molecular weight carboxylic acid (stearic acid), and a polymer-bound carboxylic acid [ethylene-acrylic acid (EAA) copolymer]. Film samples were prepared and stored in hot water at 90 degrees C and analyses were performed with a decalin extraction method as well as with FTIR techniques. The DBTDL was found to strongly catalyze the first step of the crosslinking reaction, that is, the hydrolysis. Concerning the catalytic activity of the carboxylic acids, the low molecular weight stearic acid has been shown to be a much more effective catalyst than is the polymer-bound carboxylic acid (EAA). Estimations on a molar basis give approximately a factor of five between them in efficiency. The carboxylic acids probably catalyze the hydrolysis as well as the condensation step of the crosslinking. Comparing stearic acid with DBTDL shows that the latter still is the more effective catalyst on a molar basis. Different possible catalytic mechanisms for the DBTDL and acid compounds are proposed based on the Bronsted and Lewis acids' concepts.