The author's pdf has been posted with the permission of the editor.Temperature Programmed Desorption (TPD) experiments were conducted to investigate the properties of stable surface oxides formed during low temperature oxidation of lignite chars. For both Loy Yang and Bowmans char, TPD spectra demonstrate a transition at low conversion. A linear increase is found in the fraction of remaining carbon associated with stable surface oxides as conversion increases for both chars. Compared to Loy Yang char, Bowmans char has a significantly greater number of stable surface oxides yielding CO2 during TPD. It is proposed that the abundant inorganic material in Bowmans char catalyses the formation of CO2- yielding stable surface oxides
