The synthesis Of Si3N4 by the self-propagating high-temperature synthesis (SHS) process has been carried out to evaluate the effect of NH4Cl/NH4F as an additive. A higher alpha-phase content is obtained when the rate of NH4Cl/NH4F addition decreases. The powders obtained exhibit good sintering behavior. Their mechanical properties are comparable to those of a commercial sample, although the porosity of the SHS powders is higher. This behavior might be due to the greater particle size of SHS Si3N4 powders.