In this study, the gas-to-liquid heat pipe heat exchanger was fabricated and tested, and the thermal recovery capability and thermal performance of heat pipe heat exchangers were investigated. The device consist 19 stainless steel-water heat pipes with an outside diameter of 6.2 mm, a wall thickness of 0.5 mm and a length of 300 mm. The experiment was conducted at conditions for which hot gas and cooling waters enter at temperatures of 150-250 ºC and 30ºC, respectively. The flow rate of gas through the evaporator is at the range of 0.114-0.270 kg/min, while the flow rate of water through the condenser is 0.940 kg/min. The results showed that the maximum heat transfer rate was 445.5 W, and the maximum effectiveness was 0.609. The present research was also carried out the comparison between experimental and theoretical investigation with reference to the correlation in the literature.