This thesis revolves around investigating some aspects of both supersymmetric and non- supersymmetric flux vacua of type II string theory. After providing the relevant definition of a vacuum in this setting, the framework of Generalized Complex Geometry is exposed: we review in particular the differential conditions for vacua in the presence of fluxes in this language, and we discuss their relation to integrability of the associated structures. We then survey a natural extension able to include the whole flux content into a geomet- rical picture, known as Exceptional Generalized Geometry. Fluxes are recovered in this context as a twisting of the Levi-Civita operator, from which a set of differential equations for the relevant algebraic structures is derived. These are carefully compared with the known supersymmetric constraints that a vacuum should satisfy in both cases of N = 1, 2 supersymmetries. Motivated by the application of the AdS/CFT correspondence with a reduced amount of supercharges, we obtain an effective five-dimensional supersymmetric theory, and we demonstrate in particular how a specific ansatz largely used in the string theory literature can be naturally embedded in it. We then investigate the supergravity dual to a metastable supersymmetry-breaking state by considering the most general first- order deformations of a supersymmetric solution, in order to single out the backreaction of anti-D2 branes. We conclude that unavoidable infrared singularities arise in view of the presence of anti-D2 branes perturbing the underlying supersymmetric background.

IPhT