High temperature heat exchangers (HTHE) constructed with ceramics can achieve higher temperatures of operation. Resistance to oxidation is the great advantage of using ceramics for this application. This paper presents experimental characterization of one ceramic heat exchanger composed of finned plates operating at temperatures as high as 800 degrees C and Reynolds number between 170 and 2000. The heat exchanger operates in counter-flow with air in both sides. The plates were constructed using alumina (Al2O3) with the Gelcasting technique. Thermal performance was obtained in the form of Colburn and friction factors as a function of Reynolds number. The heat exchanger effectiveness varied between 0.620 and 0.901. Progressively higher temperature was imposed to the heat exchanger prototype to cause structural failure. In addition, the design and structural integrity assessments were carried out using refined finite element computations based on real experiments regarding fracture resistance of the employed ceramic. Thermal performance of the ceramic heat exchanger is adequate and predictable using CFD simulations, but guarantee structural integrity remains challenging. (C) 2016 Elsevier Ltd. All rights reserved.