Triphenylstibinedibromide and its derivatives with tribromo-, and pentachlorophenols have been used as flame-retardant additives for polypropylene. Maximum limiting oxygen index of 31.5 against 18.2 for unfilled polypropylene was obtained in a sample containing 10 phr of triphenylstibinedibromide. However, V-0 rating in UL-94 test was observed in 20 phr flame-retardant-filled polypropylene sample, while V-2 rating was obtained even at 5 phr flame-retardant level. Thermal behavior of flame-retardant-filled polypropylene was also studied in air atmosphere by thermogravimetric analysis, and an attempt has been made to correlate the flammability with the thermal behavior. The residue obtained in isothermal treatment at 450°C for 1/2 hour in air was analyzed for antimony and halogen which establishes the role of these flame retardants in vapor phase.