The thermal decompositions of a series of tris dibromo alkyl phosphates similar to tris(2,3-dibromopropyl) phosphate (T23DBPP), alone and incorporated in poly(ethylene terephthalate) (PET) fabric have been studied by non-isothermal thermogravimetry. Kinetic evaluation revealed that the decomposition rate for tris(2,3-dibromo-3-methyl butyl) phosphate (T23DB3MBP) was the fastest followed by tris(2,3-dibromo-2-methyl propyl) phosphate (T23DB2MPP). Tris(3,4-dibromobutyl) phosphate (T34DBBP) and tris(2,3-dibromo butyl) phosphate (T23DBBP) had only marginally faster decomposition rates than T23DBPP itself. Measured decomposition rates for PET treated with the chemicals were only marginally faster than those for the untreated fabric, except during the initial weight loss stages where some decomposition of the chemicals appears to be occurring. Calculated kinetic parameters using an isoconversional method, along with regression coefficients of compensation effect plots suggest that all the chemicals behave similar to T23DBPP in having an apparent detrimental effect on the condensed phase decomposition kinetics while relying on their combustion inhibition effects to act as gas phase flame retardants.