<p>Thermal risks of ionic liquids should be greatly concerned to prevent fire accidents during industrial production, storage and transportation. This work presents the measurements and analysis of the thermal decomposition kinetics of some functionalized ionic liquids with cations of 1-butylsulfonic-3-methylimidazolium ([BSO₃HMIm]⁺), 1-propylsulfonic-3-methylimidazolium ([PrSO₃HMIm]⁺), 1-hydroxyethyl-3-methylimidazolium ([HOEtMIm]⁺), 1-ethylmethylether-3-methylimidazolium ([EOMIm]⁺), 1-cyanopropyl-3-methylimidazolium ([CPMIm]⁺) and 1-allyl-3-methylimidazolium ([AMIm]⁺) and anion of tetrafluoroborate ([BF₄]⁻). TG-DSC and TG-FTIR were used to assess the thermal stability and hazardous gas production. The results show that the thermal stability of six functionalized ionic liquids follows an order of [PrSO₃HMIm][BF₄] &lt; [BSO₃HMIm][BF₄] &lt; [HOEtMIm][BF₄] &lt; [AMIm][BF₄] &lt; [CPMIm][BF₄] &lt; [EOMIm][BF₄] based on the Tonset of TG-DTG analysis. The kinetics analysis was performed using the Flynn–Wall–Ozawa methodology. The results indicated that [CPMIm][BF₄], [AMIm][BF₄] and [EOMIm][BF₄] show larger active energy while the other three ionic liquids with sulfonic and hydroxyl-functionalized groups on cations have relatively lower active energy. Furthermore, in the low conversion stage, the sulfonic and hydroxyl-functionalized cation are more active than other ionic liquids. Allyl and cyanopropyl functionalized ionic liquids are prone to decompose with one-step reaction, while those O-functionalized ones have multi-step reaction which is possibly due to the O atom may react with the broken hydrocarbon fractures.</p>