A crosslinked polymer having perfluorocyclobutane rings is prepared in a process comprising the steps of: (a) contacting monomers having two dimerizable perfluorovinyl groups; (b) exposing the monomers to sufficient heat and for a sufficient time that a (linear) polymer containing perfluorocyclobutane rings is formed; and (c) exposing the polymer to sufficient crosslinking initiating means and for a sufficient time such that crosslinking occurs. Crosslinked polymers, so prepared are novel and have tensile strength and other physical properties enhanced over the properties of the corresponding linear polymer.