The buckwheat grains make valuable material for the food industry to compose functional food and to use it in the prevention and therapy of diseases dependent on diet. The aim of the researches was to determine the influence of thermal treatment on chemical and antioxidant properties of buckwheat grains. The material was dehulled buckwheat grains (Fagopyrum esculentum) of domestic variety Kora of harvest in 2005. The thermal treatment (160ºC, 30 min) was carried out in model laboratory experiments. The thermal process of dehulled buckwheat grains caused a decrease in the content of total starch, resistant starch fraction and dietary fibre. A decrease in total phenolic compounds content by about 5% was also observed. The ability of methanolic extracts to remove free radicals DPPHº and ABTS⁺º decreased by 6.3% and 10.9% in comparison with buckwheat grains not processed, and the TEAC (Trolox Equivalent Antioxidant Capacity) values reached respectively 7.6 and 18.0 μmol Trolox/g d.m. The stated drop of ability of buckwheat grains extracts to remove of two types of free radicals (DPPHº and ABTS⁺º) was correlated with the total phenolic compounds content (r = 0.95 and r = 0.99).