Thin films of BaFe12O19 have been grown on (00l) oriented alpha-Fe2O3 single crystal substrates. The initial stages of the reaction between BaFe2O4 thin films and hematite single crystals have been investigated using AFM and SEM. The micro structure studies showed that (00l) oriented BaFe12O19 microcrystallites formed during annealing at 900-1100degreesC. It was concluded that the surface diffusion had a dominating role in formation of thin BaFe12O19 films. Crystal growth was performed by stacking of layers with the thickness 2.3 rim, correlated with the c-parameter of the BaFe12O19 Unit cell. (C) 2003 Elsevier Science B.V. All rights reserved.