Introduction and objective Mycotoxins are toxic metabolites produced by certain types of fungi, causing pathological changes in humans and animals. The aim of this study was to assess the degree of contamination of selected cereal grains, bran and cereal products intended for children, with mycotoxins using GCxGC-TOF-MS technique. The study involved mycotoxins belonging to the type A and B trichothecenes group, including T-2 toxin (T-2), HT-2 toxin (HT-2), scirpenol (SCI), 15-monoacetoxyscirpenol (15-MAS), diacetoxyscirpenol (DAS), triacetoxyscirpenol (TAS), fusarenon-X (FUS-X), nivalenol (NIV), deoxynivalenol (DON), 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON). The study also assessed the effect of conditions in which the samples were stored, including temperature (6°C and 28°C) and time (14 and 28 days), on fungal growth and mycotoxin production. Among all studied compounds, only DAS and HT-2 toxins were detected in tested samples, with the exception of products intended for children. Measured HT-2 mycotoxin content in tested samples was in the range 83.9 – 196.4 µg kg -1 . Results and conclusions Experiments with storage conditions showed a statistically significant increase in the HT-2 toxin level after 14 days of storage in all samples, irrespective of temperature. Prolonged storage (additional 14 days) did not cause significant changes in the HT-2 content. Further analyses showed a statistically significant effect of storage temperature on HT-2 toxin levels only in cereal products intended for children after both 14 and 28 days. Interestingly, lower temperature (6°C) was more optimal then higher temperature (28°C) for the HT-2 toxin production. No significant effect of storage temperature on HT-2 level was observed for cereal grains and bran.