Equilibrium moisture content (EMC) is very important to determine the desirable conditions of grain storage, microorganisms growth which cause material deterioration, and all drying and humidification processes. This work aimed to determine the EMC of four biomaterials namely, sheep wool (animal material), kenaf, flax and cellulose plates (plant materials) under different conditions of temperature (5-30°C) and relative humidity (43-96%). The results indicated that the EMC of the four materials increased with increasing the relative humidity while, it decreased with increasing temperature. The EMC of sheep wool recorded the highest value (20.9%) followed by, kenaf (18.5%), cellulose plates (15.9%) and flax (15%) respectively. The EMC of sheep wool, kenaf, cellulose plates and flax ranged from 13.4-32.1, 12-26.8, 10.1-23.7 and 9.2-22.6 %, respectively at the ambient conditions under study. Empirical equations of the relationship between temperature, relative humidity and EMC for the materials under study were determined at different conditions