The appropriate description of heat transfer to coolants at the supercritical state is limited by the current understanding. Thus, this poses one of the main challenges in the development of supercritical-fluids applications for Generation-IV reactors. Since the thermodynamic critical point of water is much higher than that of carbon dioxide (), it is more affordable to run heat-transfer experiments in supercritical . The data for supercritical can be later scaled and used for supercritical water-based reactor designs. The objective of this paper is, therefore, to discuss the basis for comparison of relatively recent experimental data on supercritical obtained at the facilities of the Korea Atomic Energy Research Institute (KAERI) and Chalk River Laboratories (CRL) of the Atomic Energy of Canada Limited (AECL). Based on the available instrumental error, a thorough analysis of experimental errors in wall- and bulk-fluid temperatures and heat transfer coefficient was conducted. A revised heat-transfer correlation for the CRL data is presented. A dimensional criterion for the onset of the deteriorated heat transfer in the form of a linear relation between heat flux and mass flux is proposed. A preliminary heat-transfer correlation for the joint CRL and KAERI datasets is presented.