Magnetic domains, microstructure and magnetic properties of highly orientedbarium ferrite thin films with perpendicular anisotropy have been investigatedwith magnetic force microscopy (MFM), VSM, SEM and TEM. Two kinds ofmagnetic domain are energetically favourable: (a) cluster-like structure inas-deposited films grown at 770°C; (b) stripe domains in layers annealed at hightemperature (900°C). Such a difference in domain configuration can be related tomicrostructure. Small single-domain grains (70 nm) exist in as-deposited filmswhereas annealed films consist of large multidomain platelets. The magneticmeasurements (hysteresis loops and virgin curves) reveal that magnetizationreverses by rotation and wall motion for cluster-like and stripe domainsrespectively. A good agreement was established between the domain widthmeasured by MFM and that predicted by using the Kooy–Enz model(Kooy C and Enz U 1960 Philips Res. Rep. 15 7) in our stripe structure.The analyses of minor loops and virgin curves suggest that the coercivityin stripe domains is controlled by wall nucleation rather than pinning.