We describe the development of a microcalorimetric platform for accurate measurement of the heat power generated by chemical/biochemical reactions in liquid volumes of a few 10 µL, which we used to measure the heat of mixing of 1-propanol in deionized water. The system allows fast overall stabilization to a setpoint temperature with a stability of ± 1 mK. The combination of an open-well sample reservoir with a commercial nanocalorimetric chip (Xensor Integration) makes the platform easy to use and very versatile. The open-well format allows preloading a sample by pipetting, while fluidic interconnections enable injecting subsequently additional reagents.