This research aims to contribute to the discussion of ceramic objects found at the Monte Castelo shell mound (sambaqui), an archaeological site located at south west Amazonia, Brazil. The first study performed in the area in the 1980s suggests that this archaeological site is inserted within one of the oldest contexts of ceramic production in Amazonia. Until today, there have not been any studies of the physical and chemical properties of these objects to reconstruct clay procurement practices and contribute to their archaeological interpretation. With this purpose, this paper provides the results of a preliminary chemical characterization of eighty four pottery samples using instrumental neutron activation analysis (INAA) by means of the determination of Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Rb, Sc, Sm, Th, U, Yb and Zn. The compositional analysis produced substantial geochemical data that allowed comparisons of the similarity/dissimilarity between the samples by means of cluster, principal components and discriminant analysis. The results showed the existence of three different chemical groups whose dates range from 3,000 B.P. to 1,500 B.P. and are in agreement with other studies that place the Bacabal phase as the oldest ceramist culture in the Southwest of the Amazon. Additionally, this study provided a solid research framework of investigation that can be employed for more detailed and extensive future studies on ancient human occupation in the research area.