Various organophosphorus ligands with a combination of different donor sites were synthesized and evaluated by solvent extraction studies for the complexation of Am(III)/Eu(III). Among the ligands with a glycolamide backbone, those with mixed amide and PO donor sites and a central oxygen or nitrogen atom showed a reasonable extraction of Am(III) and Eu(III). Ligands with a central oxygen atom exhibited selectivity towards Eu(III), and those with a central nitrogen atom towards Am(III). Ligands with PS donor sites and a glycolamide backbone did not show any reasonable extraction. Amongst the ligands with a malonamide backbone, high extraction efficiency was observed for the ligand with electron-rich substituents on phosphorus, however, with almost no discrimination between Am(III) and Eu(III). The extraction efficiency of different ligands towards Eu(III) was confirmed by microcalorimetry.