Dedicated to Prof. Rinaldo Poli, in celebration of his 65 th birthday and outstanding contribution to chemistry and catalysis.The new bimetallic [Ru 2 (μ-Cl) 3 (CAP) 6 ]Cl (1) and monometallic cis,cis,trans-[RuCl 2 (dmso-S) 2 (CAP) 2 ] (2) complexes, bearing the water soluble cage-like phosphine CAP (1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane), were synthesized and characterized in solution by NMR spectroscopy and ESI-MS spectrometry. The complexes, endowed with high solubility and stability in water, were applied as catalysts for the proof-of-concept hydration of benzonitrile to benzamide in neat water at 100 °C, achieving high conversions with only 1 mol % of catalyst, both in single runs and in catalyst recycling experiments.