A Printed Circuit Heat Exchanger (PCHE) was tested using air and carbon dioxide as working fluids. These tests are conducted and analyzed to pave way for testing the heat exchanger with supercritical carbon dioxide (S-CO2), to obtain data on its performance for use in S-CO2 Brayton cycles. The tests have been conducted at steady state with a total of 18 data sets. Air inlet temperature has been varied from 70C to 140C. The pressures for CO2 and air were varied from 5 to 10 bars while varying the flow from 5 to 10 LPM. A 3D COMSOL model has been created to simulate the PCHE's performance and the results obtained from the simulations have been compared to the results obtained experimentally. The results show an average percentage error of 5.65% when comparing the outlet temperatures of air and an average of 5.73% error when comparing the outlet temperatures of CO2.