An (alkylhalo)silane is prepared by charging a reactor with a contact mass comprising metallic silicon powder and a copper catalyst and feeding a gas containing an alkyl halide into the reactor whereby the silane is formed by direct synthesis. The contact mass in the reactor during reaction consists of particles having a mean particle size of 5-150 mu m and containing 10-80% by weight of particles having a particle size of up to 30 mu m and 10-90% by weight of particles having a particle size of at least 90 mu m. The contact mass is well fluidized to ensure rapid and uniform reaction whereby the (alkylhalo)silane is prepared at high selectivity with a minimized elutriating loss of contact mass.
