Tert-butyl peroxybenzoate (TBPB) is thermally unstable organic peroxide, which may cause disasters such as fire or explosion when excessive heat released due to thermal decomposition. Ionic liquid is often used as a catalyst and inhibitor in engineering applications recently. This study investigated the thermal decomposition characteristics of TBPB when added two different ionic liquids which are 1-Propyl-3-methylimidazolium iodide ([PMIM][I]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) respectively with different mass ratio under DSC tests. Characteristic parameters such as the onset exothermic temperature (T-0) and heat of decomposition (Delta H-d) of samples were compared. Kinetic parameters such as activation energy E-a were computed using two isoconversional methods which were Ozawa method and Friedman method respectively. The model based (zeroth order reaction) estimation method was used to estimate TMRad at T-0 from non-isothermal DSC measurements to assess the thermal hazard of five samples. The paper aims to study the effect of ionic liquids (ILs) on the thermal decomposition of TBPB and analysis the influence of two ionic liquids on the decomposition mechanism of TBPB.