The highly non-descriptive character of biological materials resulting from their non-standard shapes and their mechanically heterogeneous structure in particular, underlies the lack of any detailed estimation of the raw materials' physicochemical qualities' influence on the course of disintegration process. Hence, it seems that the qualities expressing the relations arising during mechanical loads (mechanical and rheological properties) are especially significant. In individual tests an attempt was made for a detailed description of cereal grains' resistance parameters. These properties were defined in the single-particle compression test. Test were carried out for rye and barley grains of varying humidity (10-18%). Tests concerning the process of cereal disintegration were carried out on the stand equipped with a laboratory hammer mill. The measurements showed significant relationships between the kind of cereal, its resistance characteristics and the energy utilisation in the process of disintegration. Results of the tests and the relations were described by means of regressive equations.