A process for the preparation of alkylsilanes and alkenyl silanes by hydrosilylation of their corresponding silanes and unsaturated hydrocarbons in the presence or absence of a catalyst. A process for the preparation of polyalkenylsilanes (some of which are novel high molecular compounds) by the anionic coordination polymerization, radical polymerization or ionic polymerization of the alkenylsilanes. A process for the production of silicon carbide by using these polyalkenylsilanes as prepolymers.