The effects of potassium aluminium sulphate (K2SO4 center dot Al2SO4)(3)center dot 24H(2)O) and potassium sesquicarbonate (K2CO3 center dot 2KHCO(3)center dot 3/2 H2O) as flame retardants on fire properties of flexible polyether foam was studied. Potassium sesquicarbonate performed better at increasing the ignition time and the amount of char formed and both factors improved with flame retardant concentration. However, the afterglow time, flame duration, burn length and flame propagation rate decreased with increase in concentration. The flame propagation rates of foam samples with alum were higher than the corresponding rates with potassium sesquicarbonate. This could be attributed to the nature of their decomposition products at pyrolysing/flaming temperature. Thermogravimetric analyses showed that the flame retardants delayed the onset of degradation. The delay effect was higher with potassium sesquicarbonate (akanwu) than with potassium aluminium sulphate (alum). Again, the delay effect was affected by the flame retardant concentration.