There is described a process for preparing silylamines in and particularly trisilylamine (TSA) in high yields in a tubular laminar flow, plug flow reactor, from ammonia gas and a monohalosilane gas. The apparatus can be a tubular flow reactor comprising a first portion of the reactor defining a gas entry zone, a second portion of the reactor defining a reaction zone and a third portion of the reactor defining a separation zone, the reaction zone providing a reactant contacting region. Trisilylamine can be recovered in the separation zone in a cold trap collection vessel.