Platinum blues with the composition Pt(phen)(NHCOMe)2X (phen is 1,10-phenanthroline, X = NO3 −, CF3SO3 −, or Cl−), were synthesized starting from the complex [Pt2(NHCOMe)4Cl2]. The resulting compounds apparently have a polymeric structure with metal centers in different valence states. The reaction of the complex Pt(phen)(NHCOMe)2NO3 with H2O affords crystalline binuclear acetamidate [PtIII 2(phen)2(μ-NHCOMe)2(NHCOMe)2](NO3)2, whose structure was determined by X-ray diffraction. The reaction of the complex Pt(phen)(NHCOMe)2NO3 with HCF3SO3 leads to the decomposition of the starting compound, the reduction of the Pt atoms, and the formation of the complex [PtII 2(phen)4](CF3SO3)4. The thermal decomposition of the resulting complexes, as well as the complexes [(phen)Pt-(μ-NHCOMe)2Pt(phen)]2(NO3)4 and [Pt(phen)Cl2], under an inert atmosphere was studied by DSC and TGA. Metallic platinum nanopowders are thermal decomposition products of the complexes under study.