The creation of a very heat resistant cover for returnable orbiters and for hypersonic flying aircrafts is an actual problem in modern science and technics. Therefore, computer modelling and investigations molecular structure of various multicomponent compounds are important tasks. In the paper, based on the computer model the molecular structure and a very heat resistant of carbonitride hafnium Hf6C3N2 have been investigated by using of the semiempirical quantum mechanical method PM3. Some mechanical, electrical, optical and thermodynamic parameters of this material have been researched. Debye temperature and melting temperature have been calculated. The found theoretical value of melting temperature of carbonitride hafnium Hf6C3N2 is approximated to obtained experimental results. The block diagram of carried out investigations has been presented. The results of investigations indicate that these materials can be applied as a very heat resistant cover for hypersonic flight vehicles and returnable orbiter.