Abstract: This invention relates to an improved pouring spout of the type of ones which are detachably connected to a filling container for transferring liquid in a receiving container. These kind of pouring spout include an inlet tube for receiving liquid from the filling container, and an outlet tube telescopically mounted to slide onto the inlet tube for guiding liquid therefrom into the receiving container. The spout also comprises a liquid valve which opens and closes automatically upon sliding of the outlet tube. The current invention further comprises an air passage and an air valve for regulating an air flow inside the spout from the receiving container into the receiving container, such that the flow of liquid inside the spout stops automatically when the receiving container is full, thereby avoiding spillage of liquid. The pouring spout of the invention also resolve the problem of emanations related to the transfer of dangerous volatile and highly inflammable liquid.