Polychrome terracotta high-reliefs representing two narrative cycles and belonging to the Museu Nacional de Arte Antiga (Lisbon) were studied. The authorship, historical-artistic context and technological aspects of these artworks are still unknown. Considering the apparent similarity of materials and features of both sets, this research sought to contribute to the establishment of possible relationships between the objects and their workshops in terms of production technology and chronology. The chemical composition of terracotta paste was determined by instrumental neutron activation analysis. The mineralogical composition was acquired by X-ray diffraction. Chronological issues were studied by luminescence. This study enables elucidation of questions related with chronology, provenance and production technology, particularly raw materials and firing temperatures. Compositional results point to the use of distinct raw materials for the cycle of Saint Francis’ Life and that of The Passion of Christ, and low firing temperatures. The luminescence results point to a production of the high-reliefs in the second half of the 18th century, in accordance with art-historical studies.