Mössbauer studies of PbFe0.5Nb0.5O3samples prepared by mechanical activation of PbO, Fe2O3and Nb2O5mixture and subsequent sintering at various temperatures TSwere performed. The room temperature Mössbauer spectra consist of two doublets (D1 and D2) for the samples with TSS> 800 °C. The parameters of the doublet D1 correspond to Fe3+in the octahedron environment. Doublet D2 has a lower isomer shift corresponding to Fe3+with the coordination number 5 that indicates the presence of oxygen vacancies. Dependence of the temperature TNof magnetic phase transition on TShas a maximum at TS≈ 700 °C. The effect of Fe3+/Nb5+ordering degree and oxygen deficiency on TNis discussed. © 2017, Springer International Publishing AG.