Fuente: Materials This chapter focuses on the processing of ceramic matrix composites (CMCs) based on sol-gel methods. The fabrication of CMCs is a complicated task as it is necessary to consolidate the matrix between the fibers without impairing them. Sol-gel is a versatile technique based on the transition of a liquid colloidal solution (sol) to a three-dimensional solid network with trapped liquid (gel), behaving like a semisolid. In the context of CMCs, sols can be used for fiber impregnation, followed by gelation to consolidate the matrix. This method offers several advantages such as low processing temperatures, precise and homogenous composition control, tailorable porosity, and good infiltration and shaping capabilities. This chapter aims to provide an overview of sol-gel impregnation processes for readers of different backgrounds. First, the fundamental chemistry of sol-gel transition for the production of different ceramic components is explained. It is then explored how this technique can be adjusted for the fabrication of CMCs. Each processing step is explained—from sol formulation to the infiltration of fiber preforms, gelation, drying, and sintering—highlighting the impact of each stage on the final properties of the composites. The main limitation of this technique, related to extensive matrix shrinkage and possibly cracking, is discussed together with alternative gelation methods to address that. The combination of sol-gel with other processing techniques is also explored. At the end, examples of gelation-based CMCs are presented, showcasing what can be achieved with this technique.