  We report on the construction of four dimensional gauged supergravity models
that can be interpreted as type IIB orientifold compactification in presence of
3-form fluxes and D3--branes. We mainly address our attention to the symplectic
embedding of the U-duality group of the theory and the consequent choice of the
gauge group, whose four dimensional killing vectors are the remnant of the ten
dimensional fluxes. We briefly discuss the structure of the scalar potential
arising from the gauging and the properties of the killing vectors in order to
preserve some amount of supersymmetry.
