CO₂ fluid and silicate melt inclusions are used as geobarometer and geothermometer in the study of mafic and ultramafic nodules from various Italian volcanic areas (Vesuvius, Mt Etna, Iblean Plateau, Sardinia) and from Oahu island (Hawaii). In these volcanic areas, the CO₂ fluid and melt inclusions have been useful to examine the physical conditions of nodules genesis and to characterize the P-T history of nodules during their ascent to the surface.