Supercritical carbon dioxide (sCO2) is an environmentally friendly refrigerant used in a growing portfolio of HVAC&R products. Supercritical cooling istypically most relevant to HVAC&R application. However, there are emerging applications in the built environment such as micro-turbine systems andelectronics cooling in which heating of supercritical carbon dioxide is of interest. In this presentation, experimental work on heating of sCO2 in smallgeometries is presented. The experiments show that even in small diameters, buoyancy can significantly influence the convective heat transfer. Thus, modelsto accurately predict the heat transfer must account for these effects.