The objective of the research study was to determine the effect of moisture and comminution of seeds, and the degree of choking seeds mass in an expeller press on some selected pressing parameters and quality characteristics of flax oil. The research study comprised flax seeds of high linolenic “Bukoz” variety. The seeds tested were ground using a flaking method in a two roll laboratory mill with smooth rolls. The oils were pressed in an UNO expeller press, product of a Farmet company. It was found that the moisture of the seeds, the diameter of outlet nozzle of the press and the flaking of the seeds prior to pressing them had a significant effect on the pressing parameters and oil quality. The increase in the moisture of seeds from 6.7 % to 8.6 % caused the capacity of press to increase from 7.8 to 8.8 kg/h, the pressing yield to decrease from 81.6 % to 71.9 %, the oil temperature to decrease from 51 to 47 °C, the cake temperature to decrease from 69 to 66 °C, the content of water in oil to increase from 0.39 to 0.43 %, and the content of insoluble impurities to decrease from 4.4 to 3.2 %. The appropriate moisture level in seeds ranged between 7.5 and 9 %. Reducing the nozzle diameter from 10 mm to 6 mm caused the capacity of press to decrease from 11.8 to 8 kg/h, the pressing yield to increase from 69.5 to 77.6 %, the oil temperature to increase from 45 to 51 °C, the cake temperature to increase from 65 to 69 °C, and the content of insoluble impurities to increase from 3 to 3.3 %. The appropriate diameter size of nozzles used to process the whole seeds was 8 mm. The flaking of the seeds caused the capacity of press to increase from 8 to 9.8 kg/h, the yield of pressing to increase from 77.6 to 80.7 %, the temperature of oil to decrease from 51 to 44 °C and of cake to decrease from 66 to 65 °C, and the content of insoluble impurities to increase from 3.3 to 4.6 %. The suitable diameter of nozzle used to process flakes was 6 mm.