The invention is directed toward a vapor-liquid heat and/or mass exchange device that can be used in an integrated heat and/or mass transfer system. To achieve high heat and mass transfer rates, optimal temperature profiles, size reduction and performance increases, appropriately sized flow passages with microscale features, and countercurrent flow configurations between working fluid solution, vapor stream, and/or the coupling fluid in one or more functional sections of the desorber are implemented. In one exemplary embodiment of the present invention, a desorber section utilizes a heating fluid flowing in a generally upward direction and a concentrated solution flowing in a generally downward direction with gravity countercurrent to the rising desorbed vapor stream. To further increase the efficiency of the system, various types of column configurations can be used. Additionally, the surfaces of the microchannels can be altered to better transfer heat.