A high-temperature bonding composition comprising a silicon base polymer as a thermosetting binder is provided. The silicon base polymer is obtained from dehydrolytic condensation of a condensate precursor comprising a silane compound having at least one pair of silicon atoms tied by a crosslink composed of an aliphatic hydrocarbon, heterocyclic or aromatic hydrocarbon group, and having at least three hydroxyl and/or hydrolyzable groups. Those silicon atoms having a direct bond to the crosslink composed of the aliphatic hydrocarbon, heterocyclic or aromatic hydrocarbon group are present in a proportion of at least 90 mol % relative to all silicon atoms in the polymer.