The first objective of the study was to determine the impact of technological treatment procedures applied during the process of manufacturing buckwheat groats on the content of antioxidants in buckwheat caryopses prior to roasting (GS) and after roasting (GPOP) buckwheat, in the buckwheat hull (GŁ), in the broken groats (KŁ), and in the whole buckwheat groats (KC). The second objective was to determine the ability of water extracts of buckwheat products to scavenge DPPH^• free radicals. The technological process comprised the following phases: cleaning the caryopses; roasting (at 130 ºC during 60 min., after 15 min saturation using water vapour); maturing (24 h); sorting out I; dehulling; sorting the groats out, separating & removing hulls, and sorting out II. The contents of the following flavonoids were determined: rutin, catechin, quercetin, vanillin, kempferol, and acids: p-coumaric, o-coumaric, gallic, p-hydrobenzoesic, caffeic, sinapyl, and ferulic. Their contents were determined using a high-speed method ‘RRLC’ (Rapid Resolution Liquid Chromatography) and an SB-C18 column. The acetic acid solution with methanol was an eluent. The antioxidant properties were assessed based on the ability of extracts to scavenge the DPPH^• radical. The results obtained proved that the contents of antioxidants studied changed during the technological process. The highest content thereof was reported in buckwheat after roasting and the lowest in the whole groats. Rutin was a compound to appear in the highest amount. The process of roasting caused the contents of rutin, kempferol, quercetin, catechine, and gallic acid to increase, and the contents of p-coumaric and caffeic acids to decrease. O-coumaric and ferulic acids were found in no samples under analysis. The water extracts of the products investigated were characterized by a higher ability to scavenge the DPPH^• radical compared to BHT radical. It was found the the buckwheat prior to roasting had the highest scavenging ability, whereas the broken buckwheat groats – the lowest.