Abstract: In this study, a coating technique known as “cold spray” was developed to form a micro-porous coating on the SA508 Gr3 carbon steel heater, which was the prototypical material for the reactor vessel. On the rotatable experimental bench, downward facing pool boiling CHF experiments using a plate test section under atmospheric pressure was performed to investigate the quenching curves on the CHF limits with and without cold-spray coatings at different inclination angles. Quantitative measurements showed that the local CHF values for the coated surface were consistently higher than the corresponding CHF values for the bare surface, and that the use of cold-spray coatings could enhance the local CHF limits for downward facing boiling by more than 25%. In addition, the micro-porous coatings were stable enough after many cycles of heating and cooling.