The potential of coal fly ash was studied as a catalyst in the air oxidation of aqueous sodium sulfide (Na 2 S) solutions in the temperature range of 303-333K. The rate of oxidation was found to be independent of the initial concentration of Na 2 S in the range of 5.80x10 - 2 -28.45x10 - 2 kmol/m 3 . The effects of fly ash loading, source of fly ash, speed of agitation, air flow rate, fly ash particle size were also studied. Experimental results suggested a film-diffusion controlled reaction mechanism and 4% fly ash loading intensified the reaction rate by a factor of 3.5 over that of without fly ash at 303K. The deactivation of the catalytic effect of fly ash was found to be less than 31% even after fifth repeated uses.