Abstract: Systems and processes for gas phase-phase synthesis of trisilylamine. One system includes a reactor vessel having a top, bottom, and sidewall having an inner surface. The reactor vessel includes inlets for gaseous reactants, and a gas inlet for an inert gas. In certain reactors the gas inlets are positioned near the top of the reactor vessel and configured to inject the reactant gases in the reactor substantially vertically and downward therefrom. Other reactors are cyclonic-shaped with tangential feeding of the gases. One or more baffles having a peripheral edge and substantially horizontally positioned in the reactor to define a reaction zone above the baffles and a separation zone below the baffles. The baffles are positioned in the reactor vessel such that there is a gap between the baffle peripheral edge and the inner surface of the reactor vessel. Certain systems and processes include mechanical or static mixers.