A device for thermal or thermo-chemical treatment, in particular calcination, of material, in particular battery cathode material, having a housing and a process chamber in the housing, in which there is a process chamber atmosphere during the treatment and which defines a conveying level. The material, or carrying structures loaded with the material, at the conveying level can be conveyed in a conveying direction into and/or through the process chamber by a conveying system. An entry airlock gate defines an inlet level and includes an airlock gate chamber, an airlock gate inlet and an airlock gate outlet, as well as an inlet conveyor which is designed so that the material or carrying structures loaded with the material at the inlet level can be conveyed through the airlock gate inlet and into the airlock gate chamber. The conveying level and the inlet level are different from one another. A method for thermal or thermo-chemical treatment, in particular calcination, of material, in particular battery cathode material, in which the material or carrying structures loaded with the material at the conveying level and the inlet level are conveyed at different heights.