Whilst considerable research has been conducted on the stability of plastics additives during processing, there is, on the other hand, a lack of studies on the stability of the same additives in food simulants in the published literature. In the work presented a systematic study has been undertaken on the stability of five selected commercial plastics additives (Irganox 3114, Irganox 1035, Irganox 245, Irganox 1098 and Irgafos P‐EPQ) in the three EU‐official aqueous food simulants (distilled water, 3% aq. acetic acid and 15% aq. ethanol) and in an alternative fat simulant (95% aq. ethanol) under two different time/temperature exposure conditions (10 days at 40°C and 1 h at 100°C). To enable quantitative analysis of the additives for this investigation, a simple and rapid HPLC method with UV detection was developed. The results obtained showed that the four Irganox‐type additives under investigation were practically stable under the applied exposure conditions in all of the employed food simulants. Only Irganox 3114 exhibited a relatively low degree of instability in the ethanolic food simulants. Concerning Irgafos P‐EPQ, a mixture of at least seven constituents, a remarkable degradation in ethanol and acetic acid solutions was observed. The developed HPLC method is also considered to be applicable for stability testing of other Irganox‐type additives both in aqueous and fatty food simulants.