iron doped (0.25–7.5% molar) hydrothermal nano-SnO2 was characterized by electron magnetic resonance (EMR) and Mössbauer spectroscopies. Only a small fraction of transition metal ions are in magnetic ordered state, contrary to the similar crystallographic compound TiO2. Temperature dependences of spectra suggest that by increasing iron concentration, or annealing temperature, iron ions migrate to nanoparticles surfaces forming disordered iron oxides.