An apparatus for producing oxidic nanocrystals from metal organic compounds or volatile inorganic compounds comprises an apparatus which includes a first vaporizer which is connected to a first carrier gas stream to produce a first reactant gas stream, a second vaporizer is connected to a second carrier gas stream to produce a second reactant gas stream the first and second reactant gas streams are connected to a first feed line and flow heated reactor wherein the reactants are heated and reacted to provide oxidic nanocrystals which are unagglomerated having a mean particle size of up to 20 nanometers.