The synthesis and structural analysis of six new lanthanide imidazolium carboxylates are discussed. The first mononuclear lanthanide imidazolium carboxylate salts, [{(L)2M}3+{NO3 −}3], M=Sm (1), Gd (2), Dy (3) and Y (4), were synthesized from the reaction between zwitterionic tris-imidazolium carboxylate and corresponding metal nitrate salts. The presence of monodentately coordinating carboxylate groups in 1–4 are confirmed by FT-IR spectra. The isostructural salts 1–4 are discrete tricationic monomer. To the best of our knowledge, the ionic salts 1–4 are the first structurally characterized mononuclear lanthanide imidazole carboxylates. The coordination environment of M(III) is fulfilled by six carboxylate oxygen atoms of ligands in distorted octahedron geometry. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim