The objective of the research study was to determine the changes in the chemical composition of grains of the ‘Finezja’, ‘Retr’ and ‘Nikol’ wheat cultivars resulting from the processes of extrusion and infrared radiation. The grains were moisturized to obtain 15 and 15 % of moisture therein and extruded at a temperature of 110/135/175/180/124 °C as well as irradiated by infrared radiation at 100 and 130 °C for 30 and 90 s. In the material analyzed, the following was determined: dry matter, crude ash, ether extract (crude fat), total protein, crude fibre, NFE, fibre fractions (ADF, NDF, CEL, HCEL and ADL), and starch. In the wheat grains irradiated at a temperature of 130 °C for 90, a significant (p ≤ 0.05) decrease in the content of crude protein was reported (about 7 % in the ‘Finezja’ grains and 5 % in the ‘Retro’ grains) and in the content of crude fat (4 % in the ‘Finezja’ grains). In the analyzed material, the thermal processes performed caused the content of crude fibre to decrease (the highest decrease was in the extruded ‘Finezja’, ‘Retro’, and ‘Niko’ grains, respectively: 38, 26, and 39 %). Additionally, the content of starch decreased in the extruded and irradiated ‘Finezja’ grains (respectively: 18.5 % and 10 %). The same phenomenon was also found in the case of dietary fibre fraction. The highest losses referred to the following: ADF (24 % – ‘Nikol’); NDF (12 % – ‘Retro’ and 9 % – ‘Nikol’); CEL (17 % – ‘Nikol’); and HCEL (16 % – and 10 % ‘Retro’ – ‘Nikol’). An unfavourable effect of the processes applied was the increase in ADL (7 % in the irradiated ‘Finezja’ wheat grains and 11 % in the extruded ‘Retro’ grains). The best modification of the chemical composition was achieved by the process of extruding the ‚Finezja’ and ‘Nikol’ wheat grains that were moisturized to 25 % prior to the process; the infrared irradiation process resulted in the best modification of the chemical composition of the ‘Nikol’ wheat grains.