The book investigates the potential use of fly ash as a secondary raw material. Emphasis is placed on the effects of the admixture of power plant fly ash from lignite combustion on the properties of ceramic bodies in the building industry. Keywords: Illite-Based Ceramics, Power Plant Fly Ash, Drying Process, Particle Size, Particle Morphology, Heavy Metals, Mineral Compositions, Microstructure, Differential Thermal Analysis, XRD Analysis, Bulk Density, Water Absorption, Porosity, Pore Distribution, Thermal Diffusivity, Internal Friction, Hardness, Mechanical Strength, Flexural Strength.