OMPLEX formation reactions involving Cd(II), pyridine -2- carboxylic acid ( picolinic acid, PA) and various biorelevant ligands (L) containing different functional groups are investigated at 25 ºC and I = 0.10 M (NaNO3). The ligands (L) used are amino acids, peptides and DNA constituents. The results showed the formation of Cd(II)-(PA)-(L) complexes with amino acids and DNA constituents, peptides form both Cd(II)-(PA)-(L) complexes and the corresponding deprotonated amide species Cd(II)-(PA)-(LH-1). The relative stabilities of ternary complexes are compared with those of the corresponding binary complexes in terms of ∆ log K values. The concentration distribution of the complexes in solution was evaluated.