A field of thermal treatment of ceramic materials is provided, and relates to a method for thermal treatment of a solid ceramic part in a microwave cavity, the direction of the electrical field E being substantially uniform in an empty cavity, comprising the steps that consist of placing, in the cavity, at least one ceramic part surrounded by at least one first susceptor with dimensions, material and arrangement configured to emit infrared radiation, each first susceptor including at least one first main surface, each first main surface being an adjusted surface in which the cone distances are parallel to the electrical field E, and of emitting the microwaves into the cavity.