The significance of mass transfer enhancement in polymer electrolyte fuel cells (PEFC) is presented and studied in this work based on experimental investigation. A novel structure of reactant gas distributors in PEFC is proposed for mass transfer enhancement purpose. For the PEFC with novel gas distributors, it is found that the large drop of the cell voltage, generally caused by a weak mass diffusion, is postponed to occur at relatively higher current density even though the same or less amount of air is fed when comparing to a PEFC with gas distributors in conventional structure. As a result, the maximum obtained electrical power in a PEFC and a PEFC stack both are dramatically improved under both free convective and forced convective airflow conditions.