In the last decade very high dielectric constant have been reported in ceramic materials based on titanium oxides [1-3]. However, these high dielectric constants were reported in the literature only for small sized round pellets with diameter of approximately 10 mm’s. The reported results that showed extremely large dielectric constants have potential for commercial use. In our research, we were able to manufacture large ceramic slabs with high dielectric constant, with dimensions of 20*30*3 mm. During this research, the stability and electric properties of these materials were analyzed. Furthermore, an extended analysis of the dielectric constant, parallel resistivity and the temperature behavior of the ceramic materials as a function of the environmental humidity was conducted[4-8]. The paper shows how temperature of the oven during the ceramic production influences the dielectric constant and parallel resistivity of the ceramic slabs. The obtained ceramic samples were tested by XRD and electronic scanning microscope. The following compositions were investigated: BaZrxTi1-XO3, Ba1-X SrXTiO3, CaCu3Ti4O12 The research shows that for large slabs the Curie temperatures and the width at half maximum are different than for small ones. In addition, the dielectric constants and the parallel resistivity are extremely sensitive to humidity, meaning that the correct values of these parameters should be measured at humidity of ~ 10%.