The paper presents the assessment of the number of pellets with fissures, length, diameter, hardness and mechanical endurance of pellets depending on the composition and temperature of their storing. Pellet samples used in the research were produced in a pelleting machine with the 8 mm matrix openings diameter. Pine sawdust and pine sawdust with 30 or 50% addition of beech sawdust were used as raw material for production of pellets. The research was carried out on the pellets stored for 3 hours in 20, 40 and 60ºC temperature. Mechanical endurance of pellets produced of pine sawdust and stored in 20ºC was 98.2% whereas for pellets produced of pine sawdust with 50% addition of beech sawdust was 96.8%. The research proved that the composition significantly influenced the results of mechanical endurance of the investigated pellets in the accepted temperatures. Temperature of storing pellets did not significantly influenced the results of their hardness.