It exists as brown to black crystalline powder, but single crystals are golden and exhibit metallic conductivity.

OsO2 can be obtained by the reaction of osmium with a variety of oxidizing agents, including, sodium chlorate, osmium tetroxide, and nitric oxide at about 600 °C.

[2][3] Using chemical transport, one can obtain large crystals of OsO2, sized up to 7x5x3 mm3.

Single crystals show metallic resistivity of ~15 μΩ cm.

A typical transport agent is O2 via the reversible formation of volatile OsO4:[4] OsO2 does not dissolve in water, but is attacked by dilute hydrochloric acid.