Reactive deposition processes of tantalum carbide are studied experimentally and theoretically in the Ta–C–Si–O–F system. It is shown that Sio 2 substantially affects the carbide formation process. This is expressed in a decreased efficiency of tantalum transfer from the source zone to the crystallization zone, the possibility of bilateral transport of tantalum to carbon and carbon to tantalum, the complicated composition of condensed phases in the equilibrium with the gas phase. Aspects of preparing single crystal tantalum oxyfluoride are considered.