Thermal stability of polysulfone (PSF) and its zeolite LTA hybrids with two different zeolite contents has been investigated by using differential thermal analysis (DTA) and thermogravimetric (TG) analysis measurements, and the thermal experiments in air were conducted at a constant heating rate in the span of 5–30 K/min. The thermal characteristics were evaluated based on TG and DTA results. Two‐stage thermal decomposition is seen to mainly occur in the range of 700–970 K and the zeolite LTA added has considerably influenced the thermal behavior of PSF. Two isoconversional model‐free Flynn–Wall–Ozawa and Coats–Redfern methods are employed to perform kinetic analysis of the mass loss versus temperature data, resulting in activation energy and pre exponential factor values. The activation energies obtained over the whole conversion range for two zeolite composites are considerably lower than those of pure PSF, possibly related to the catalytic effect of zeolite LTA added. The materials conversion functions D5 and D3 are found to more appropriately describe thermal degradation of PSF and its zeolite LTA hybrids. Using the kinetic parameters and conversion functions, the temperature‐dependent thermal conversion curves under different heating rates have been successfully recast, leading to excellent calculation results.