Tert-butyl hydroperoxide (TBHP) is a typical alkyl hydroperoxide for industrial applications and is used as a curing agent or free radical initiator for polymerization reactions in the petrochemical industry. Thermal instability associated with the thermal runaway evaluation of aqueous TBHP is hazardous during chemical processes or in storage. In this study, both differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2) were used to characterize the thermally incompatible hazards and adiabatic runaway features of aqueous TBHP with various acids and alkalis. From the thermal analysis experiments, we integrated the enthalpy of energy-rich aqueous TBHP reacting with acids and alkalis to normalize various temperatures of the exothermic decomposition and heat production. Self-reactive ratings on incompatibly thermal hazards were characterized using various thermokinetic parameters of the adiabatic calorimetry method, such as the initial exothermic temperature (T-0), self-heating rate (dT/dt), pressure rise rate (dP/dt), and pressure temperature profiles. Compared to aqueous TBHP reacting with different contaminants, the adiabatic runaway reaction via VSP2 indicated that TBHP was intrinsically incompatible with self-reactive behaviors. The characterization of the exothermic decomposition and incompatibility hazards of aqueous TBHP were evaluated using calorimetric methodology.