Disclosed herein is a composition comprising amino-functional polysiloxanes of high purity and their preparation. Also disclosed herein is an aminoalkyl-functional polysiloxane, a process for purifying this aminoalkyl-functional polysiloxane, a process for preparing the composition, a use of the composition, a polyorganosiloxane-polyorgano block copolymer, a process for the preparation of a polyorganosiloxane-polyorgano block copolymer and a shaped, formed and/or extruded shaped article.