AbstractNitrosylruthenium-dibutylphosphate complexes were prepared by the reaction of trinitrate-nitrosylruthenium with dibutylphosphoric acid and by the reaction of nitrosylruthenium hydroxide with dibutylphosphate in alkaline solutions. The products are mixtures of compounds of indefinite composition, some of which are monomeric and others polymeric. Complexes were also prepared by the reaction of trinitrato-nitrosylruthenium with monobutylphosphoric acid and dinitro-nitrosylruthenium with dibutylphosphoric acid.