The conditions of the formation of rare earth element (Y, La-Lu) dipicolinates were studied, and their quantitative compositions and solubilities in water at 293 K were determined (10(-2) to 10(-3) mol dm-3). The IR spectra of the hydrated complexes were recorded and their thermal decomposition in air was determined. During heating the hydrated dipicolinates Ln2(C7H3NO4)3 . nH2O (n = 9-25) lose some or all of their water molecules of crystallization water in one, two or three steps; then the anhydrous or hydrated complexes decompose either directly to the oxides (Y, Ce, Sm-Dy, Tm-Lu) or with intermediate formation of oxocarbonates Ln2O2CO3 (La, Pr, Nd, Ho, Er).