The objective of the paper was to evaluate the impact of biomass subjected to pelleting and diameter of pressing openings of a matrix of a pelleting machine on unit consumption of energy and quality of pellets. Virginia mallow biomass (Sida hermaphrodita R.) was investigated. The pelleting process was carried out on a pelleting machine with a flat matrix with the set of pressing rolls. Matrices with three diameters of pressing channels 6, 8, 10 mm were used for pelleting. Pelleting attempts were carried out at the material moisture which was 10, 15 and 20%. It was found out that energy consumption of the process of pellet production from Virginia mallow biomass depended on the raw material moisture and on diameter of pressing channels in the matrix of a pelleting machine. Unit consumption of electric energy during the pelleting process was within 45.3 and 70.2 Wh·kg-1. The lowest value was reported for moisture of 15% and diameter of pressing channels of 10 mm. Durability of the obtained pellets was within 88.9-93.5% of pellets. The highest durability was in case of pellets obtained at the moisture of 15% but higher durability was obtained at lower diameters of pressing openings. The highest relative density was in case of pellets obtained at the moisture of 15% and it was 1133.6-1094.8 kg·m -3 but density got reduced along with the increase of a diameter of channels.