The complexation of Eu(III) with Polyacrylic acid (PAA) and alumina-bound polyacrylic acid (PAA-Al2O3) was studied at pH 5 in 0.1 M NaClO4. The experiments were carried out for two polyelectrolytes at 5000 Da and 50000 Da. The quantitative description of the interaction of Eu and PAA showed the formation of a 1:1 Eu:PAA complex and the existence of similar binding modes ("sites") of Eu with both polymers. Interaction studies of Eu(III) with alumina-bound PAA particles were carried out in conditions where their overall surface charge were equal to 0. The description of the data indicated the existence of a similar site in binary and ternary systems for high Eu loading. For low Eu loading, the existence of a new site on PAA-Al2O3 particles resulting from the PAA-Al2O3 interaction was suggested.