The acid-base properties, protonation activity, and complexing abilities of two substituted beta-diketones have been studied. The equilibrium constants of dissociation (pK(a)) were obtained at constant ionic strength (I = 0.5 M) in the pH 2.0-7.5 region. Protonation processes have been investigated in a strongly acidic solution of HCl for the determination of protonation constants (-pK(H)). All received acid-base parameters characterize both ligands as more acidic compounds than thenoyltrifluoroacetone. The study of complexation with 11 lanthanides (Ce, Nd, Pr, Sm, Eu, Gd, Dy, Er, Tm, Yb, and Lu) was carried out in glycine buffer. The determined values of formation constants for monocomplex species lie in the region from S.S to 6.9 logarithmic units. Using DFT procedures, the optimal computational protocol for describing the studied equilibria has been found.