The objective of the research study was to determine the effect of flaking seeds and hydrothermally treating seed flakes on some selected parameters of pressing process and the quality characteristics of linseed oil. The research material consisted of flaxseeds of the ‘Bukoz’ high linolenic variety (IWNiRZ, Poznan, PL). The seeds were flaked in a two-roll laboratory mill equipped with smooth rolls and a 0.2 mm slot. The flakes produced of 20 % of moisture were hydrothermally treated in a laboratory incubator, at a temperature of 50 °C, over a period of 3 h. The hydrothermally treated flakes were dried in an air flow dryer. The oils were pressed in an UNO-SE expeller press manufactured by Farmet (CZ). The flaking of seeds contributed to the increase in the press capacity from 8.5 to 10.6 kg/h as well as in the oil yield from 72.0 to 73.5 %; further, it contributed to the decrease in the oil temperature from 48 to 43 °C and in the cake temperature from 68 to 64 °C. The flaking of seeds caused the amount of insoluble impurities in oil to increase from 3.2 to 4.0 %. The hydrothermal treatment of raw flakes caused the press capacity to increase from 10.6 to 13.5 kg/h, the oil yield to increase from 72.0 to 73.5 %, the oil temperature to increase from 43 to 47 °C, and the cake temperature to increase from 64 to 68°C. The latter process resulted in the increase in the acid value of oil by 0.16 mg KOH/g and in the increase in the peroxide value by 0.65 meq O₂/kg. The flaking of seeds causes the amount of insoluble impurities in oil to increase whereas the hydrothermal treatment of flakes aids the hydrolysis and oxidation of the oil being produced.