The ruthenium complexes [Ru(BIm-2-COO)2(PPh3)2]·CH3OH·H2O (1), [RuCl2(MeIm-2-COO)(PPh3)2] (2) and [Ru(NCS)2(MeIm)2(PPh3)2]·CH3OH (3) have been prepared and studied by IR, 1H, 31P NMR, UV–Vis spectroscopy and X-ray crystallography. The complexes were synthesized by the reactions of [RuCl2(PPh3)3] with 1H-benzimidazole-2-carboxylic acid (BIm-2-COOH) or 1-methyl-1H-imidazole-2-carbozylic acid (MeIm-2-COOH) and in the case of complex (3) with admixture of NH4SCN in methanol solutions. The experimental studies were complemented by quantum chemical calculations which were used to identify the nature of the interactions between the ligands and the central ion and the orbital compositions in the frontier electronic structures. Based on a molecular orbital scheme, the calculated results allowed the interpretation of the UV–Vis spectra obtained at an experimental level. The luminescence properties of the complexes were determined.