Abstract: The invention relates to apparatus for heat treatment of material in pieces at high temperature, especially for firing ceramic material. In this apparatus supports in the form of elongated support elements are provided on carrier elements rotatable about fixed axes, the supports are guided in the transport direction and are spaced a clear distance from one another at right angles to the transport direction. This results in even heat treatment of the material, a reduction in the energy consumption, shortening of the transit time, and a significant reduction in the construction and running costs.