The Tertiary Krakowiec clay deposit in Kolbuszowa-Kupno is one of the biggest in south-eastern Poland. The clay is illitic in character. Together with illite there occur other clay minerals (kaolinite, smectites, chlorites), non-clay ones (quartz, calcite, feldspars) and organic matter. Taking into account grain size distribution, one can point to the possibility of applying this mineral raw material for the production of such structural clay products as lighweight brics and blocks. The clay studied is characterized by high plasticity as well as relatively low make-up water and drying shrinkage. The natural radioactivity coefficients f1 and f2 for the clay studied are significantly lower than permissible Polish limits for structural clay products and their raw materials. During firing of clay samples the compressive strenght and shrinkage of the body increase while the permeability decreases. These processes are intensified at a temperature of 1050oC. During firing of the clay studied, mainly water vapour and carbon dioxide are released. The lack of the emission of such detrimental volatiles as SOx and HF is advantageous from the environmental viewpoint. The comparison of technological properties of products made of clay of the Kolbuszowa-Kupno deposit, manufactured by traditional method and by fast firing method indicates that the time of the production process can be remarkably reduced without significant influence on technological parameters of the ceramic body obtained.