The integral quadratic separation (IQS) framework is a specialization of topological separation theory to the case where operators are described by (or embedded in) integral quadratic constraints. IQS applies both to regular and descriptor system representations. Thanks to this feature, IQS provides a methodology for deriving sequences of LMI conditions with reducing conservatism. It has been applied for robust performance analysis of systems with uncertainties and delays. In this paper the methodology is adapted for the first time for region of attraction evaluation in the case of systems with saturations. Results are illustrated on a launcher attitude control example with saturated inputs.