A b s t r a c t. Principal component analysis (PCA) was applied to laboratory measurements of eight descriptive parameters of the pelletability of six raw materials (maize, rice, soybean, cassava, alfalfa and meat meal) and of mixtures of the first three. The two-fold aim was to select the most relevant criteria for classifying the raw materi­als and to verify the additivity of the mixtures. The best criterion was the work of compression by an axial load (up to 200 MPa) applied to the meal in a cylindrical cell. Maize and rice mixtures were additive. The compression of soy­bean was improved by the presence of maize and rice.