Mesoporous multiphase amorphous–crystalline Bi2O3 nanopowder with the specific surface area of 23 m2/g is obtained using pulsed electron beam evaporation in vacuum. The influence of thermal annealing (200–300°C) of the powder in air has been investigated. Droplets 2–5 nm in size are formed on the surface of all large nanoparticles comprising the framework of 3D agglomerates of the nanopowder due to extrusion of liquid bismuth from bulk upon cooling.