A study of solutions of the oxalate complexes of berylium by ir and Raman spectrometry has demonstrated the formation of three complexed species: BeC2O4, Be(C2O4)22−, and Be3(OH)3(C2O4)33− regardless of the ratio used. Each complex is characterized by specific vibrational frequencies which are independant of the pH of the solution. It was possible to determine the concentration of each species as a function of pH, as well as its stability constant, by measuring the intensifies of certain characteristic bands in the Raman scattering spectrum. [Journal translation]