The performance of high temperature air combustion (HiTAC) depends oil the heat regenerator efficiency and on the way fuel is mixed with furnace gases. In this work. combustion of a fuel jet of gasol (>95% of propane) was investigated experimentally. Experiments were carried out in steady-state conditions using a single jet flame furnace. The jet of fuel was co-axially injected into high temperature exhaust gases generated by means of a gas burner also fired with gasol. Thus. instead of highly preheated and oxygen depleted air, which was normally used by other researches for such studies. this work has used high temperature and low oxygen content exhaust gases as the oxidiser. A water-cooled fuel nozzle was used to control fuel inlet temperature. Influence of the oxygen content in the oxidiser. at temperatures of 860-890 degreesC, on the flame visibility and the reactants composition was investigated. The combustion of gasol in hot flue cyases appeared to be very stable and complete even at very low oxygen concentration. The oxygen concentration in the oxidiser was found to have a substantial effect on flame size, luminosity, colour, visibility and lift-off distance. Reduced oxygen concentration increases the flame size and lift-off distance, and decreases luminosity and visibility. The HiTAC flame first became bluish and then non-visible at sufficiently low concentration of oxygen in the oxidiser. In this work. results are presented for the constant ratio between fuel Jet velocity and velocity of co-flowing flue gases. ThB ratio was equal to 26. (C) 2004 Elsevier Ltd. All rights reserved.