This work presents experimental data from a downward fired cylindrical combustion chamber at 60 kW(th) equipped with a swirl burner. The swirl flame was aerodynamically stabilized in two different oxy-fuel (O-2, CO2) atmospheres with 21 vol% and 25 vol% oxygen content in the oxidizer. Flame details were studied by means of local gas concentration measurements for CO, CO2, H2O, total hydrocarbons, NO and SO2. The concentrations were measured at different axial and radial distances from the burner using a tempered suction probe and a Fourier Transform Infrared Spectrometer (FTIR). Additionally wall temperatures were measured by two-color-pyrometry. Based on all these measurements the flames were described in terms of reaction zones, pyrolyses, volatile combustion as well as formation of pollutants. (C) 2016 The Combustion Institute. Published by Elsevier Inc. All rights reserved.