We consider type II string theory in space-time backgrounds which admit eight supercharges. Such backgrounds are characterized by the existence of a (generically non-integrable) generalized SU(3) × SU(3) structure. We demonstrate how the corresponding ten-dimensional supergravity theories can in part be rewritten using generalised O(6,6)-covariant fields, in a form that strongly resembles that of four-dimensional N = 2 supergravity, and precisely coincides with such after an appropriate Kaluza-Klein reduction. Specifically we demonstrate that the NS sector admits a special Kähler geometry with Kähler potentials given by the Hitchin functionals. Furthermore we explicitly compute the N = 2 version of the superpotential from the transformation law of the gravitinos, and find its N = 1 counterpart.