The invention concerns a micro-heat exchanger having a microstructure of channels (2) arranged at least in one matrix element (1) in the form of a plate and circulating at least one coolant, said matrix element (1) having upper and lower surfaces (5, 6) as well as lateral surfaces (3, 4). The invention is characterized in that the channels (2) are open on the upper surface (5) and/or on the lower surface (6) and closed on the lateral surfaces (3, 4).