Cellular ceramics have become essential in various industrial applications. This chapter explores the types, shapes, and characteristics of cellular ceramics, and their potential uses in space propulsion and catalysis. There are different varieties, including foams, honeycombs, and reticulated structures, classified by their composition, structure, and production processes. These materials are favored for their high porosity, low density, excellent mechanical strength, and thermal stability. Their large surface area and enhanced mass transfer capabilities make them effective as catalyst supports in processes like hydrocarbon reforming, oxidation, and hydrogenation, where they immobilize catalytically active species to boost activity and selectivity. In space propulsion, cellular ceramics are used in thruster components due to their ability to withstand high temperatures and maintain structural integrity under harsh conditions.