The combustion performance of H-2-rich model syngas was investigated by using a premixed swirl flame combustor. Syngas consisting mainly of H-2 and CO was blended with components such as CH4 and CO2 in a mixing chamber prior to combustion at atmospheric condition. The global flame appearance and emissions performance were examined for high (H-2/CO = 3) and moderate (H-2/CO = 1.2) H-2-rich syngases. Results showed that higher H-2 fractions in the syngases produce lower NOx emissions per kWh basis across all equivalence ratios tested. CO emissions are equivalence ratio dependent and are less affected by the H-2 fraction in the syngas. Increasing CO2 diluent ratios result in the decrease of NOx, particularly for moderate H-2-rich syngases. In contrast, syngas without CO shows an increase of NOx with increasing CO2 for fuel-lean mixtures. Addition of CO2 increases the lean blowout limit of all syngases. Higher fraction of H-2 produces lower lean blowout limits due to the characteristics of high diffusivity of hydrogen molecules and high flame speed that assist in the stabilisation of the flame under flame-lean conditions. The range of blowout limits for moderate and high H-2-rich and pure hydrogen syngases under diluent ratios up to 25% were within the range of phi = 0.12-0.15. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.