The complex formation between a cyclic ligand glutarimidoxioxime (denoted as HLIII in this paper) and UO22+ is studied by potentiometry and microcalorimetry. Glutarimidoxioxime (HLIII), together with glutarimidedioxime (H2LI) and glutardiamidoxime (H2LII), belongs to a family of amidoxime derivatives with prospective applications as binding agents for the recovery of uranium from seawater. An optimized