[en] Aqueous complexes of M(III) f-element ions with the inorganic ligands CO₃^2- and SO₄^2- have been investigated using the highly-sensitive speciation techniques TRLFS and ESI-MS. The Eu(CO₃)_i^3-2i (i=1-3) species have been characterized by TRLFS, and the stoichiometry of the limiting complex Eu(CO₃)₃^3- have been confirmed by solubility measurements of NaEu(CO₃)₂(s) at high ionic strength. Temperature effect on Cm(III) carbonate complexes is evidenced by the TRLFS technique. Investigation on sulphate complexation has been done at various ionic strengths by TRLFS on Eu(III) and by ESI-MS on La(III). New thermodynamic data are obtained by both techniques, which are consistent with literature data. (authors)