The present invention relates to a device (1) for microwave treatment of a material, wherein the device defines a treatment space (3) for receiving the material to be treated by the microwaves (14). The device comprises at least one microwave-generating unit (10) arranged outside the treatment space and adapted to provide microwaves (14) into the treatment space for treating the material, a microwave absorbent (21), and a housing (20) made of a non-microwave transparent material, in which housing the microwave absorbent (21) is arranged. The housing (20) is provided with a plurality of openings (29) for microwaves (15) to pass through to the microwave absorbent (21).