Abstract: The solubilities of scandium-oxalate in solutions of various concentration of ammonium oxalate and ammonium perchlorate (the latter is to maintain a constant ionic strength of 2) were measured at 25℃. The existence of complexes ions [ScC₂O₄]⁺[Sc(C₂O₄)₂]^- and [Sc(C₂O₄)₂]^3- have been revealed from the treatment of experimented data by useing of qraphic extrapolation. The solubility product of scandium oxalate was also calculated to be 1.22×10^-22 (μ = 2, pH=1). The succesive stability constants of the complexes formed were calculated by two ways: relaxation method and a least-squares technique on a computer. The results are as follows: β₁ = 1.94 × 10⁸; β₂ = 5.5 × 10¹⁵; β₅ = 2.0 × 10¹⁶.