A dry mixture of ZnO and alpha -Fe2O3 was annealed at 1200 degreesC; the progress of the formation of the ferrite was monitored by XRD and XPS analyses at different time intervals. The presence of octahedral zinc cation was observed along with the regular tetrahedral Zn in the sample that had undergone 30 minute heat treatment. After three hours of heating, pure normal zinc ferrite was formed. The Zn 2p(3/2) peak binding energy, intensity and line shape were analyzed extensively to show the diffusion of ZnO and the growth of ferrite at different stages of heat treatment. Analysis of the Fe 2p(3/2) line-shape supported the substitution of Fe2+ by zinc cations during ferrite formation. The binding energy values of the Zn 2p levels for stoichiometric and non-stoichiometric ferrites were also determined and surface segregation of the zinc was observed by XPS in the non-stoichiometric ferrites.