Humidifier

A humidifier for fuel cells includes a housing with a heat-exchange plate formed therein, the plate defining first and second gas passages having gas inlets and outlets, respectively; a plurality of apertures formed on the plate; and a plurality of reservoirs fixed under the apertures and filled with a water absorbable and permeable stuffing material for trapping and storing water. The water permeable stuffing material may be disposed in the first gas passage. Cool, dry oxygen/air is channeled to the first gas passage and conveyed to an oxygen/air inlet of the fuel cell, and high-temperature, high-moisture exhaust gas discharged from the fuel cell is introduced to the second gas passage, such that water and heat of the exhaust gas in the second gas passage are recycled by the heat-exchange plate and conveyed to the first gas passage, thereby achieving the humidification effect and improving electricity-generating efficiency of the fuel cell.