t Catalysts are substances that are widely used in the industry to increase the speed of chemical reactions. Because of the need for high temperatures in some of the chemical reactions required, catalysts are needed to maintain their stability. Carbon/Carbon composites can be introduced as a suitable option for high temperature catalytic applications. In this study, the construction and characterization of C/C composites are investigated using the CVI process. For this purpose, carbon fiber felt (CF) was used as a preform. Methane and hydrogen gas were used as gas and carrier gas respectively. Then the carbon felt and nickel catalyst is produced and characterized. Finally, the effect of the presence of nickel particles and carbon nanofibers on the rate of carbon sequestration in the CVI process is investigated. The design and construction of the reactor CVI process and selection of the optimal temperature (1050 ?C) composite samples were produced with different time period. Then, in addition to studying these structures using SEM, XRD, FTIR and Raman electron microscopy, their physical and mechanical properties were studied. The results of C/C composite on carbon fiber showed that with increasing CVI process time up to 195 hours, the density of samples produced from 0.208 g/cm 3 to 1.616 g/cm 3 and its flexural strength and modulus increased to 73.28 MPa and 1.77 GPa, respectively. The carbon deposition mechanism is up to 105 hours of layered type and has a RL structure. However, with the increase in CVI process time, the mechanism of the deposition has changed, and it forms DS and SL structures on the RL structure layers. Also, the results of the study of the production of nickel catalyst, which was carried out using the process of impregnation of carbon felt in a solution of nickel nitrate, along with the processes of drying, calcination and reduction, showed that the nickel particles formed on the surface had a satisfactory catalytic activity. On the other hand, the results of the presence of nickel catalytic particles on carbon fiber and the creation of carbon nanofiber at temperatures up to 700 ° C showed that carbon diposition in the CVI process could be significantly increased.