Dynamic Light Scattering (DLS) and spectrophotometric studies were carried out to investigate the aggregation behavior of dinonyl phenyl phosphoric acid (DNPPA) under varying experimental conditions such as aqueous phase acidity, nature of diluents, and ligand concentration. The aggregation of 0.05 M DNPPA/n-dodecane and the extraction of U(VI) and rare earth elements (REE) decreased with increase in nitric acid concentration. This observation was further supported by changes in absorption spectra of DNPPA pre-equilibrated with increasing concentrations of nitric acid. (C) 2013 Elsevier B.V. All rights reserved.