The transesterification between ester and alkoxysilane groups in the range of temperatures 100-250 degreesC takes place only in the presence of dibutyltin oxide (DBTO) as efficient catalyst. Without DBTO, no reaction is observed. This interchange reaction has been used to crosslink ethylene-co-vinylacetate copolymer. Kinetic and theology data have shown that only two alkoxide groups from one tetrafunctional alkoxysilane molecule are involved in the crosslinking reaction.