A novel hybrid system integrating high-temperature proton exchange membrane fuel cell (HT-PEMFC) with air gap membrane distillation (AGMD) is proposed to cogenerate electricity and freshwater. A mathematical model is established to evaluate the proposed system performance from both exergetic and energetic perspectives considering various irreversible effects, from which effectiveness and practicality of the proposed system are examined. Calculation examples reveal that maximum power density of the integrated system allows 83.4 % greater than that of the basic HT-PEMFC system, meanwhile, the according exergy destruction rate density is declined by 3.14 %. Furthermore, considerable sensitivity analyses indicate that the proposed system performance is benefited by elevating the feed water temperature while worsened by increasing the coolant water temperature, air gap width and thickness of hydrophobic membrane or feed water NaCl concentration. The feasibility of AGMD as an effective exhaust heat harvesting alternative is proved. The results acquired may be helpful in designing and optimizing such an actual hybrid system.