AbstractIntermediate phases and reactions occurring on decomposing diammonium hydrogen phosphate, ammonium para molybdate, sodium tungstate dihydrate and ammonium meta vanadate were established by thermal analysis and X‐ray examination.These salts promote fabric degradation at low temperatures but are effective at high temperatures. Diammonium hydrogen phosphate produced maximum amount of gases, absorbed the highest amount of heat and gave the highest fire retardation above 350