Rice is one of the most strategic food staples in the world, accounting for large contribution of world farming lands. Rice by-products like straw, bran and husk, produced before rice milling, have great number of applications. Rice husk is a material of great importance, which is either discarded or burned out, near the farms and rice milling factories mostly because of low digestible nutrients. Although, rice husk has a high heating value used as biomass fuel and to produce biogas. The most outstanding drawback on biomass exploitation is low bulk density and lack of cost-effectiveness of its maintenance and traortation. So in this study, the desirable pelleting conditions, including high density, appropriate durability and less compressive energy to make rice husk pellet, were evaluated. The most important pellet parameters are moisture, exerted pressure and particle size. The rice husk initial moisture during harvesting was about 20% (w.b.), reduced to 6% after milling and stocking. The bulk density of the rice husk was about 71.7 kg/m 3 .In order to make pellet, the rice husk were tested in four moisture contents of 6, 9, 13 and 20% (w.b.), three compressive forces of 7000, 10000 and 14000 N and four particle sizes, prepared using three sieve opening of 2, 3.36 and 5 mm, as well as, un-milled rice husk. Rice husk loading was carried out by a cylinder and a piston using Universal Tension/Compression Testing Machine. The pellet quality was determined in different moisture levels, compressive forces and particle sizes in five replications in the form of factorial experiment in a completely randomized design (totally 240 experiments). To specify the pellet durability, a durability determination instrument was made as per ASAE S269.4. Also, stress relaxation was dealt with in four pellet samples with better density and durability and less consumption energy. Analysis of variance showed that different treatments affected all measurement variables significantly in confidence level of 1%. 9% (w.b.) of moisture content led to maximum durability, while 20% caused the minimum one. The input energy was diminished as moisture content increased due to the lubricant role of moisture content during compressing period. As pressure force increased, the pellet density was intensified so that the maximum durability of the pellet was achieved in 10000 N. Pellet durability was also enhanced as particle size increased. Generalized Maxwell model with two elements was fitted into pellet stress relaxation data. Bulter and Mc Colley model predicted rice husk density well, with a high R 2 value. With respect to bulk density of rice husk pellet, stocking space demand reduced to 0.09 that of initial, leading to reduction of traortation and shipping expenses. Un-milled rice husk together with moisture content of 6% (w.b.) were the best treatments for a durable pellet and appropriate density. It was achieved under a compressive pressure of 471 MPa, requiring a 41 mm thickness of the die to reach. Keywords : biomass, biogas, wastes, rice husk, pellet