Adsorption studies of counterions carried by the ruthenium(II) complexes (Bu4N)2[Ru(Hdcbpy)2(NCS)2] (1), (Bu4N)4[Ru(dcbpy)2(NCS)2] (2), and [Ru(H2dcbpy)2(NCS)2] (3) (dcbpy = 2,2‘-bipyridyl-4,4‘-dicarboxylate, Bu4N = tetrabutylammonium) on TiO2 have been carried out by using thermoanalytical techniques, NMR, and ATR−FTIR spectroscopic methods. The thermogravimetric analysis (TGA) data of the adsorbed complexes 1 and 2 on TiO2 show the presence of 1 and ≤1.3 cations coadsorbed per ruthenium center, respectively. These complexes in the adsorbed state on TiO2 show remarkable stability in air atmospheres at high temperatures up to 180 °C. The only process that is observed at lower temperatures is the dehydration, which occurs between 40 and 110 °C. At high temperature the processes are deamination of the tetrabutylammonium counterion as well as decarboxylation and decomposition of the complex between 200 and 400 °C. The NMR data of the desorbed complexes 1 and 2 from the TiO2 surface show the presence of 1 and...