Abstract: A new type heat-resistant silicone-polyurethane, which contains polysiloxane chain units of the general formula (II) with diisocyanato end groups and with polyurethane bonds in the chain —OCN—Z—NH—CO—O—X—O—CO—(NH—Z—NH—CO—O—X—O—)m—CO—NH—Z—NCO—??(II) wherein X is the molecular fragment containing the siloxane chain, Z is the molecular fragment containing the alkyl chain, m is an integer between 1 and 20—and/or polysiloxane chain units of the general formula (IV) with diisocyanato end groups and with polyurethane bonds in the chain —OCN—X—NH—CO—O—Z—O—CO—(NH—X—NH—CO—O—Z—O—)m—CO—NH—X—NCO—??(IV) wherein X is the molecular fragment containing the siloxane chain, Z is the molecular fragment containing the alkyl chain, m is an integer between 1 and 20—as crossed-linked polymer units and a process for the synthesis of thereof.