A vapor-liquid contact tray and downcomer assembly is provided with louvres which serve to impart a horizontal directional flow to the liquid exiting the downcomer and/or the vapor passing through the tray. The downcomer includes a bottom plate which closes the outlet region of the downcomer and includes a plurality of louvres presenting generally vertical openings in the direction of liquid flow across the underlying tray. The downcomer receiving area in the underlying tray can include similar louvres. The louvres redirect the vertical momentum of the liquid and vapor streams to a generally horizontal momentum as the liquid exits the downcomer and as the vapor rises through the tray. In other embodiments, the louvres in either the bottom plate or the downcomer receiving area of the tray are replaced with apertures which do not block the vertical momentum of the stream passing through the apertures. An enhanced vapor-liquid active area on the tray results from the use of the louvres.