Abstract: An apparatus for reducing the moisture content of a material, such as grain, has a variable volume chamber, which in use is filled with the material. Material within the chamber is heated by heating means to reduce its moisture content. A pumping means is connected to the chamber to pump off fluid from the chamber, whereby a sub-atmospheric pressure can be maintained in the chamber. In use, the pressure differential between the inside and the outside of the chamber is carried by material within the chamber, and the chamber reduces in volume so that no substantial pressure load is carried by walls of the chamber. The heating means can comprise steam pipes extending across the chamber or cylindrical heating elements formed from plates which define ducts for the steam or other heating fluid.