This article proposes a kinetic and thermal study of the formic acid perhydrolysis in a semibatch process at various hydrogen peroxide concentrations (5.32-8.21 mol/L), formic acid molar inlet flow rates (0.04-0.22 mol/min), reaction temperatures (30-60 degrees C), and catalyst amount (0.0-10.6 g). A cation-exchange resin, i.e., Amberlite IR-120, was used as a catalyst. Synthesis and decomposition of peroxyformic acid were modeled by coupling the energy and mass balances, and a pseudohomogeneous model for the reaction kinetics. A nonlinear regression method was used to estimate the kinetic parameters, such as rate constant, and thermal parameters, such as reaction enthalpy. The knowledge of these parameters allows the determination of maximum temperature of the synthesis reaction (MTSR), the time to maximum rate under adiabatic condition (TMRad), and the criticality classification. These safety parameters are important to properly design the industrial reactor.