An osmium chloride with the chemical formula of Os_xCl₃ (x = 0.81) was synthesized and its crystal structure and thermodynamic properties were investigated. Os_xCl₃ crystallizes in a layered CdCl₂-type structure with the triangular lattice partially occupied by Os ions on average. However, on microscopic length scales, the triangular lattice is composed of nano-domains with a honeycomb arrangement of Os ions, as observed by electron microscopy and Raman scattering experiments. Magnetization and heat capacity measurements revealed an absence of magnetic long-range order down to 0.08 K, while a broad peak in heat capacity at 0.15 K may indicate a short-range order in the local honeycomb lattice. Os_xCl₃ may exhibit certain aspects of the Kitaev spin liquid that are expected for a perfect honeycomb lattice of osmium trichloride.