Titanium silcides have been formed on monocrystalline (111) silicon substrates by rapid thermal annealing (RTA) of Ti layers deposited on Si at 700–800 °C for 1 to 240 s. The phase composition is dependent on the annealing temperature and time: at 700° and 750 °C for short annealing, TiSi and TiSi2 are observed. At 800 °C and by increasing the exposure time at 700 ° and 750 °C, only TiSi2 is detected. The growth of the total silicide thickness is found to be faster for RTA than for conventional furnace annealing and governed by two different mechanisms depending on the phases formed: in the range 700–750 °C, and 750–800 °C, activation-energy values of 2.6 ± 0.2 and 1.5 ±0.2 eV are found, respectively. For a thin deposited Ti layer (< 100 nm), the whole Ti is finally transformed into TiSi2 with 20@ μω cm resistivity. For thicker Ti thicknesses, titanium oxide stops the reaction.