Benzoyl peroxide (BPO), historically, due to its wide applications around the world, has caused many serious fire and explosion accidents. In this paper, in order to prevent such accidents, thermal hazard analyses of synthesis of benzoyl peroxide were studied. Firstly, in order to obtain thermal hazard coefficients, the exothermic processes with different alkaline solutions were studied by RC1e (Reaction Calorimeter). The alkaline solutions are NaOH, NH4HCO3 and Na2CO3, respectively. Secondly, the thermal decomposition of BPO product was studied by PHI-TECIlto analysis the thermal stability. Finally, the possibility of runaway reactions and thermal risks of synthetic process were evaluated according to the Stoessel criticality diagram. In the first stage, the test results of the reaction heat (Delta H-m), heat release rate (q(r)) and adiabatic temperature rise (Delta T-ad) with different alkaline solutions were NaOH > Na2CO3 > NH4HCO3. In the second stage, according to the analysis of experimental data, the heat release rate of reaction with NH4HCO3 solution was the slowest, while the Maximum Temperature of the Synthesis Reaction (MTSR) and the adiabatic temperature rise (Delta T-ad) were lowest when using Na2CO3 solution. The time needed to reach the maximum reaction rate under the adiabatic condition (TMRad) was 0.83 h when using NaOH solution. The temperature was 38.24 degrees C when TMRad is 24 h (T-D24). The evaluation results of the process showed that the risks of reactions with NaOH solution or NH4HCO3 solution were not acceptable. Only the risk of the reaction with Na2CO3 solution was acceptable. Therefore, the safety level of synthesis of benzoyl peroxide can be significantly improved by using Na2CO3 solution. Research in this paper can not only improve the safety level of BPO reaction and storage processes, but also provide technical support for stability criterion of BPO decomposition reaction. (C) 2016 Elsevier Ltd. All rights reserved.