This paper presents the behavior of a binary system in a short-path distiller in the stationary region where there is no temperature change in the liquid flow. The model used is a wiped film one and the heat transfer is supposed to be sufficient to ensure the evaporation process. A relationship between the heating surface, the initial concentration, the overall throughput and the concentration change inside the distiller is established. The quality and quantity of the output hows are also deduced, as well as the limit of purification which can be obtained.