Cai and Chen have proposed a new iterative linear integral isoconversional method that is capable of providing more accurate values of the activation energy than the traditional linear isoconversional methods (Cai, Junmeng, Chen, Siyu, 2009. Journal of Computational Chemistry 30, 1986-1991). However, an analysis of the estimation of confidence intervals for the activation energy determined by this iterative linear integral isoconversional method is still missing. Therefore, this short communication focuses on estimating realistic confidence intervals for the activation energy calculated by the isoconversional method. For this purpose, a comparison of confidence intervals estimated using the Vyazovkin-Sbirrazzuoli corrected Student's percentiles (Vyazovkin, Sergey, Sbirrazzuoli, Nicolas, 1997. Analytica Chimica Acta 355, 175-180) and a nonparametric method has indicated that the use of the Vyazovkin-Sbirrazzuoli method tends to overestimate confidence intervals for three heating rate estimates. The new corrected Student's percentiles for realistic 95% confidence intervals theta(n-2,0.975) of 2.9, 2.5 and 2.3 for three, four and five heating rate estimates, respectively, can be used to obtain realistic confidence intervals for the activation energy computed by the iterative linear integral isoconversional method. (C) 2011 Elsevier Ltd. All rights reserved.