Abstract: Processes for improving the in vivo function of factor VIII by shielding exposed targets of the factor VIII comprise a) immobilizing the factor VIII by interaction with a group-specific adsorbent carrying ligands manufactured by organic-chemical synthesis, for preventing polymer coupling to reactive amino acids of the immobilized factor VIII, within or adjacent to interaction domains; b) activating a biocompatible polymer; c) conjugating the activated biocompatible polymer to external sites of the immobilized factor VIII; and thereafter d) eluting the conjugate from the adsorbent. Processes for administering factor VIII comprise subcutaneously, intramuscularly, intradermally or intravenously administering a conjugate of factor VIII and a biocompatible polymer, and methods for treatment of hemophilia A comprise subcutaneous, intramuscular, intradermal or intravenous administration of a conjugate of factor VIII and a biocompatible polymer.