A new class of glass-ceramic nanocomposite systems with a uniform distribution of SnO 2 nanocrystals dis-persed within an amorphous silica phase is fabricated in the form of thin films by using sol–gel processing. In this work, experiments with (100-x)SiO 2 -xSnO 2 nanocomposite thin films with (x = 25 and 30 mol%) doped with Er 3+ ions (concentrations of 0.5, 1 and 2 mol%) are presented. The focus has been both to determine the effect of rare-earth doping on the growth of SnO 2 nanocrystals as well as the distribution of the Er 3+ ions within the ceramic structure. Vibrational spectroscopic assessments have proven the glass-ceramic nature of the samples. EXAFS and photoluminescence spectra show that the rare-earth ions exist in both amorphous and crystalline phases. Moreover an energy transfer from SnO 2 nanocrystals to erbium ions on excitation at 351 nm is demonstrated.