Mechanisms of the processes in condensed phase tend to occur in multiple steps that have different rates. Their kinetics is
very often described by the single-step approximation. The first attribute of the approximation is the substitution of a generally
complex set of kinetic equations describing the complex process by the sole single-step kinetic equation. The other attributes
of the approximation are the separability of the temperature and conversion functions and the additivity. The temperature
function for the best fit of experimental data may not be the Arrhenius relationship. The main strength of the single-step
approximation is that it enables a mathematical description of the kinetics of solid-state reactions without a deeper insight
into their mechanism. The low trustworthiness of far extrapolation is a weak point.
A new temperature function, derived from the observed dependence of the isoconversional temperature on heating rate, is suggested.
Using the new function, extrapolation of the accelerated thermooxidative tests has been performed for 26 experimental data
sets. The data cover a wide range of materials from polyolefins and other polymers to biodiesel, edible oils and dried milk.
It has been found that the extrapolation from high-temperature data to ambient temperature provides estimations corresponding
with experience. Coefficients of variability of the adjustable parameters occurring in the new function are low so enabling
to make trustworthy stability predictions.