The acid-base interaction between a polyelectrolyte and an ionisable drug could lead to the formation ionic complexes. The resulting physicochemical properties of such nanostructures could reflect changes in solubility, stability and drug-release pattern. This study was aimed to establish if diclofenac solubility could be modified by the formation of Eudragit® E and diclofenac polyelectrolyte drug complexes, which were prepared through the solvent evaporation method. The solid state was characterized by infrared spectroscopy and X-ray powder diffraction, and solubility was determined. The results suggested that complexes were formed in each case, they were called: EuD50, EuD50Cl10, EuD50Cl25, and EuD50Cl35. The drug apparent solubility presented values 431 and 1,498 times higher for EuD50Cl25 and EuD50Cl35 complexes respectively using water as solvent, and 3,674 and 10,412 times higher in physiological solution compared with free drug. It was concluded that the complexes have different solubility to the one of the parent drug and, therefore, they showed potential applications in the design of homogeneous liquid dosage forms.