The present research studied a set of phyllite clays from several deposits in southeast Spain. These phyllite clays have traditionally been used as sealing material to impermeabilize roofs, embankments, ponds, construction and waste landfill, with recent applications in the preparation of new mortars. However, studies on thermal behaviour and ceramic properties of phyllite clays have been scarce. The present research showed a summary of previous characterization studies on representative phyllite clays from these deposits with additional results. Mineralogical, by X-ray diffraction, and chemical, by X-ray fluorescence characterization of these samples were summarized. Thermal analysis methods (DTA-TG and thermal diffractometry) were applied to achieve a more complete mineralogical characterization. Several phyllite clay samples were selected for a ceramic study by firing pressed powdered samples up to 1300 degrees C. Sintered or vitrified materials, with porosities almost zero, were obtained from these phyllite clays after firing at 1100-1200 degrees C, with apparent densities between 2.1 and 2.4 g cm(-3). Higher firing temperatures (> 1250 degrees C) produced deformation and expansion of the ceramic bodies. These results allowed obtain the vitrification temperature (T-v) and the temperature of the maximum bulk density (T-d). According to the previous mineralogical and chemical characterization and the values of these parameters, the phyllite clay samples were classified in three varieties, as follows: (1)Micaceous, characterized by predominant layer silicates, mainly muscovite or illite, alkaline elements (mainly K2O higher than 3.5 mass%) and lower values of both T(v)and T-d, (2)Quartzitic, with predominant quartz and SiO(2)and intermediate values of T(v)and T-d, and (3)Carbonaceous, characterized by predominant dolomite, medium contents of CaO and MgO and higher values of both T(v)and T-d. These results are interesting for the application of these phyllite clays as ceramic raw materials.