Puffed grains made from whole wheat, corn or rice grains are ready-to-eat breakfast cereals that do not require additional preparation. Two recipes for puffed grain coatings were developed in the previous studies. Sunflower oil was used in the coating, which may affect storage stability. Due to lipid hydrolysis, free fatty acids may be released, causing rancid off-flavour. The aim of this study was to determine the changes in the acid value of lipids and sensory attributes of sweet-coated puffed wheat grains ‘Badyrak vanilla’ (BV) and ‘Badyrak with whey’ (MC) depending on temperature during their eight-month storage. The products were packaged in metallised polypropylene pouches, 30 g each. The acid value was studied monthly at different storage temperatures (20 ± 2 °С and 4 ± 2 °С). In puffed wheat grain products, 65% of fatty acids are polyunsaturated, 25% monounsaturated, and 10% saturated. The high proportion of unsaturated fatty acids over saturated makes oil more susceptible to oxidation. Literature studies and sensory evaluation of puffed wheat grains allowed setting a limiting acid value at 4.0 mg KOH gE−1 lipids. The increase in acid value was storage temperature dependent. Thus, the acid value exceeded the established limit in the fifth month for MC and the sixth month for BV when stored at 20 ± 2 °С. At the same time, noticeable changes in puffed wheat grain flavour were observed. The temperature coefficient (Q10) for MC was 2.0, whereas for BV it was 1.5, indicating that the acid value increase in MC was more affected by temperature than that in BV.