The application of a positive electric field on a Pd(0)–carbon aerogel nanocomposite enhances the reaction rate of the Mizoroki–Heck reaction. By contrast, when a negative potential is employed the reaction is inhibited. On the other hand, chronoamperometry measurements have revealed the polarizing current intensity as an indirect measure of the reaction evolution. The cationic nature of the reaction intermediates was unambiguously confirmed and a polar mechanism has been finally proposed.