The performance of air-to-air heat exchanger has been investigated with rotating porous plates newly developed in this study. With an equal interval of 18 mm, the rotating porous plates are installed inside the heat exchanger where the hot and cold airs enter at opposite ends. When flowing in opposite directions by the separating plate installed in the center of the rotating porous plates, the airs give and receive the heat each other. Dry bulb temperature is set by adjusting heat supply at heater. In order to measure the temperature distribution of the hot air side inside heat exchanger, the thermocouples are inserted between the plates. The first location of thermocouple is 10mm downstream from the inlet of heat exchanger, and succeeding ten locations are aligned at an equal interval of 18mm. From the experiment of air-to-air heat exchanger with the rotating porous plates, the heat transfer rate increased as both air flow rate and RPM of the rotating porous plate increased. It was found that the overall heat transfer coefficient increased with the increase in RPM of porous plate at the conditions of the same air flow rate.