The Karstedt catalyst-catalyzed ambient-condition hydrosilation reactions in hexane of a monomeric vinyl-containing carboranylenesiloxane, 1, and three-branched siloxane crosslinker monomers were discovered to produce elastomeric network polymers at very rapid rates of formation. The flexible and transparent films of the saturated elastomeric network polymers were observed to possess low glass-transition temperatures (below -35 degrees C). Similar hydrosilation reactions at two different reactant ratios involving a diethynyl-containing carboranylenesiloxane, 2, and the siloxane crosslinkers produced partially hydrosilated and completely hydrosilated polymeric networked systems, which were transparent and elastomeric at room temperature. The glass-transition temperatures of all the polymeric systems formulated from 2 were below 0 degrees C. The elastomeric polymeric networks from 1 and 2 were found to have degradation temperatures in the range of 500-550 degrees C. (c) 2005 Wiley Periodicals, Inc.