Complex formation equillibria of [Pd(DAP)(H2O)2]2+ (DAP = 1,3-diaminopropane) with Cl−, OH−, cyclobutane dicarboxylic acid (CBDCA), amino acids, peptides and DNA unit constituents have been investigated. Stoichiometries and stability constants of the complexes were determined at 37°C and 0.16 M NaNO3 ionic strength. The results showed the formation of 1:1 complexes with amino acids and CBDCA. Peptides form both 1:1 complexes and the corresponding deprotonated amide species. DNA constituents form both 1:1 and 1:2 complexes. [Pd(DAP)(CBDCA)] was isolated and characterized. The concentration distribution of the complexes in solution was evaluated.