The molecule of the title compound, [RuH(C6H8BN4)-(C18H15As)(2)(CO)]. H2O, is a discrete monomeric complex which has the hydride, carbonyl and dihydrobis(pyrazol-1-yl)borate ligands in equatorial positions, and two trans-positioned AsPh3 ligands. The geometry around the Ru-II atom is distorted octahedral. In addition to the water dimer formed by strong intermolecular hydrogen bonds, two possible weak intramolecular hydrogen bonds have been observed within the complex.