A study of the nature of growth of gallium arsenide on substrates of various crystallographic orientations was conducted in a closed tube system. It is concluded that the dominant growth direction is in the (111) direction. Growth rate studies were conducted at various temperatures and pressures. It was found that the transport of matter is not dependent on a single mechanism, but rather on a combination of diffusion, convective and laminar flow, each contributing to greater or lesser extent depending on the conditions of growth.