The thesis entitled "Micromechanical Characterization and Simulation of the Effect of Environmental Aging in Structural Composite Materials” represents the first doctoral thesis fully developed at the IMDEA Materials facilities since its research activities started at the beginning of 2008. The thesis has been co-supervised by two Senior Researchers of the Institute, Dr. Carlos Gonzalez, head of the group of Structural Composites and Dr. Jon M. Molina, head of the group of Nano and Micro-Mechanics. The research conducted within this thesis has been co-funded by the European project MAAXIMUS (FP7 Transport) and the Regional Government of Madrid through the research personnel support program.