Finally, XAS analysis of Ru-CTF sample after 9 catalytic cycles is reported in Figure (green trace) together with that of RuO2 (red trace), confirming the absence of the latter and therefore the molecular integrity of the Ru complex active site. The edge position in the XANES spectrum indicates that the metal center oxidation state remains between Ru(II) and Ru(III). The Fourier transformed EXAFS spectrum of Ru-CTF sample after 9 catalytic cycles provides evidence that the coordination environment of the Ru center has been rearranged with respect to the initial [Ru(tda)(py)2] complex, consistent with the coordination of an H2O ligand and the formation of the active form of the catalyst [Ru II (tda-k-N 3 O 0 )(py)2(OH2)], responsible for water oxidation catalytic activity.