Some new organoarsenic ligands were synthesized to investigate their potential as separating agents for trivalent lanthanide ions. Organofluoro-substituents were employed to improve the acid strength of new arsonic and arsinic acids to enable these to complex the metal ions in the lower pH region. Existing synthetic methods of simple alkyl and aryl derivatives of arsonic and arsinic acids were reviewed, modified and combined in order to prepare larger bulkier analogues with potential as extractants.