Fiber-matrix reaction zone product formation and growth kinetics at 850 and 900°C in silicon carbide (SiC) reinforced Ti-6Al-4V have been studied by thin-foil transmission electron microscopy. The major reaction product is titanium carbide, which is sandwiched between a layer of Ti5Si3 and a fine-grained mixture of titanium carbide and Ti5Si3. The large volume fraction of titanium carbide compared to titanium silicide results from the presence of a carbon-rich layer at the surface of the fibers. Growth of the reaction zone and consumption of the fiber surface layer are nonuniform, with greater reaction occurring where the fiber contacts beta phase in the titanium matrix. During exposure at 850 and 900°C, the reaction products exhibit parabolic growth, with the titanium carbide growing at a faster rate than the titanium silicide. After consumption of the carbon-rich fiber surface layer, however, the titanium silicide growth rate increases over that of titanium carbide. Reaction zone growth rate and fiber surface layer consumption rate are faster at 900°C than at 850°C.