The abundant supply of coal globally and its energy content per unit mass make the use of this fuel an attractive option for power generation. However, with increasingly strict environmental regulations imposed on greenhouse gas emission technologies the future use of coal in its current form is questionable. One solution to reduce pollutant emissions is oxy-combustion with coal-derived syngas, which can provide a method of using coal efficiently with carbon capture. This paper presents a study of the radiative heat release properties from oxy-syngas and oxy-methane flames. This is relevant since the radiative properties of prospective oxy-combustion systems are not fully known. In many oxy-fuel systems the flue gas stream is recycled and premixed with the fuel and oxidizer to reduce flame temperatures. It is estimated that the radiative heat transfer from these recirculated gases will significantly increase due to the increased emission of radiation from CO2 and H2O in the 1.2 mu m to 5 mu m wavelength range, which can impact future combustor design models. Motivated by this, this work aims to provide a study of the global and spectral radiation properties of oxy-syngas combustion and how relevant variables affect radiative emissions. Theses variables include the effect of CO2 acting as a diluent, percentage of H-2 in the fuel, firing input, and the effects of equivalence ratio on the flame's radiative heat release and spectral radiation of CO2 and H2O. The current study reveals that the radiative heat release factor of syngas flames decreases at higher firing inputs. It was also observed that the radiative heat factor decreased at high hydrogen concentrations. An increase in heat release factor is also measured at higher recirculation ratios of CO2. (C) 2015 Elsevier Ltd. All rights reserved.