Ascorbic acid (AA) degradation and colour changes, measured by the lightness index (L*), were determined in cashew apples (at low dissolved O2 concentrations) heated at high temperature (100-180 _C) in a hermetically sealed cell. A nonisothermal method was developed to estimate thermal degradation kinetics. The results showed that reaction kinetics during heat treatments were well represented by first-order reactions. The temperature dependence of the kinetic constants was described by an Arrhenius type equation. The activation energy (Ea) for AA degradation and lightness index were 94 ± 3 and 98 ± 3 kJ mol)1, respectively. The reaction rate constant at 140 _C for AA degradation (64 · 10)5 ± 3 · 10)5 s)1) was twice that for the lightness index change (33 · 10)5 ± 2 · 10)5 s)1). Results allow generating temperature profiles of heat processes that would help preserve the AA of cashew apples as well as control the colour formation during high-temperature processes.