A method and apparatus of producing inorganic semiconducting nanoparticles having a stable surface includes providing an inorganic bulk semiconductor material milled in the presence of a selected reducing agent. The reducing agent acts to chemically reduce oxides of the semiconductor material, or prevent the formation of such oxides to provide semiconducting nanoparticles having a stable surface, allowing electrical contact between the nanoparticles. The milling media and/or one or more components of the mill include the selected reducing agent. The milling media or mill are typically composed of a metal selected from the group comprising iron, chromium, cobalt, nickel, tin, titanium, tungsten, vanadium, and aluminum, or an alloy containing one or more of these metals. Alternatively, the selected reducing agent includes a liquid contained in the mill during milling, which is typically an acidic solution containing any of hydrochloric, sulphuric, nitric, acetic, formic, or carbonic acid, or a mixture thereof.