In a microstructure apparatus for heating and atomizing a fluid with an inner body received in an outer tube, circumferential microstructure passages are formed into the inner surface of the outer tube or the outer surface of the inner body so as to form a flow passage which is provided with an inlet connector and heating means are incorporated into the inner body for heating the fluid conducted through the microstructure flow passages under pressure, the microstructure fluid passages extending spirally around the inner body so as to proved for a relatively long microstructure fluid flow passage which is open at the axial end thereof for discharging the fluid heated pressurized therein through the open axial end.