The reaction between chlorophosphazenes and silicon alkoxides has been studied as a means of preparing temperature‐stable thermosetting resinous materials. If the silicon alkoxide is polyfunctional in straight‐chain lower alkoxy groups the usual reaction is elimination of alkyl chloride and formation of a thermosetting resinous product. The mechanism of this reaction is discussed. Other reactions occurring in the treatment of chlorophosphazenes with silicon alkoxides are also discussed. Asbestos laminates which retain much of their strength when heated to 500° for 50 hours in air can be prepared from the thermosetting resinous products resulting from the reaction between chlorophosphazenes and silicon alkoxides.