Abstract: A liquid storage reservoir of which the internal space defined by the body, and, the upper and the lower covers, has mounted therein a hollow post interconnecting these covers and having its internal space communicating with the internal space of the reservoir for escape of vapors of the liquid being stored, the open end of the post extending beyond the internal space of the reservoir. The upper and lower covers are hollow and communicate via conduits extending in the body along the generatrix thereof, the open end of the hollow post entering the internal space of one of said covers, the internal space of the other cover communicating with a vessel for collecting condensed vapors of the stored liquid. The disclosed reservoir is particularly suited for storing easily evaporating and volatile liquids, because it practically eliminates their evaporation losses.