The deposition rate of SiC on carbon‐coated Nicalon fibers from methyltrichlorosilane in hydrogen was measured as a function of temperature, pressure, total flow rate, and simulated reactant depletion. The results, together with kinetic information on the stability of methyltrichlorosilane, led to two conclusions: (1) two different mechanisms of deposition can occur depending on whether the methyltrichlorosilane has an opportunity to dissociate into separate silicon‐ and carbon‐containing precursors, and (2) the deposition rate is strongly reduced by the generation of byproduct HCl. The data were fitted to a simple etch model to obtain a kinetic expression that accounts for the significant effect o