Abstract <p>The uncertainty associated with the kinetic parameters of condensed phase reactions can be quantified by constructing their confidence intervals. Narrow intervals signify a high degree of accuracy in the parameter estimates, whereas broad intervals reflect considerable uncertainty in the estimated values. In this study, we present a methodology based on factorizing the reaction rate into a temperature-dependent rate constant and a conversion function to determine the confidence intervals for the kinetic parameters of condensed phase reactions. This is achieved through multiple linear regression analysis on isoconversional kinetic data obtained from several nonisothermal experiments. The delta method is employed to estimate the variance of conversion function and its confidence interval. The activation energy and its confidence interval are obtained using the Friedman method. Additionally, using the distribution of the difference in means between two populations, we can determine the confidence interval for the pre-exponential factor. The proposed method utilizes the Šesták–Berggren model to approximate the conversion function and therefore, it can be used for simple&#xa0;reactions as well as complex reactions that exhibit single peaks in their reaction rate curves. The technique was applied to both simulated reactions and experimental data regarding the thermal decomposition of polymer coating of an optical fiber. GNU Octave/MATLAB codes were provided for readers to employ this method with their own data.</p> Graphical abstract <p></p>