Vania Sordoni Reduction Scheme for Semiclassical Operator-valued Schr\"odinger Type Equation and Application to Scattering (224K, Postscript) ABSTRACT. We obtain a general reduction scheme for the study of a selfadjoint semiclassical Schr\"odinger operator with operator-valued potential by the construction of almost invariant subspaces and we apply such results to scattering theory for matrix-valued operators.