Bi2O3 particles 70 to 90 nm in size were prepared with the polyol method. According to this method a suitable metal precursor (e.g. halogenide, acetate, alcoholate) and a defined amount of water were heated in a high boiling alcohol (e.g. diethylene glycol). Based on temperatures up to 180 degreesC crystalline alpha -Bi2O3 particles were formed. The material was isolated by centrifugation and characterized by XRD and SEM. The size of Bi2O3 particles in colloidally stable diethylene glycol suspension as well as in diethylene glycol/water mixtures was determined with laser diffraction methods. These suspensions were used to prepare homogeneous thin Bi2O3 particle layers on planar glass substrates.