Our team at the Naval Research Laboratory has demonstrated that an ultrathin film of nanoscale, disordered ruthenium dioxide, designated RuO₂ nanoskin, can be deposited from commercially available precursors onto metal, ceramic, semiconductor, polymer, and salt substrates using scalable, atom-efficient, low-temperature, liquid-phase, self-limiting electroless deposition. The electrical conductivity of the resulting nanoskins can be tuned over three orders of magnitude by calcining without ripening the particles comprising the film. On the basis of optical, electrical, structural, thermal, microscopic, mechanical, electrochemical, and chemical state measurements, we categorize this disordered, nanoscale oxide as a member of a rare quadrant of electronic materials: one that exhibits a high concentration of electronic carriers (n) of low mobility (m). The remarkable physicochemical properties of RuO₂ nanoskins point to the importance of expressing functional materials in disordered, forms.