In this study, tin ferrite nanoparticles (SnFe2O4) were synthesized using sol–gel, solvothermal, and co-precipitation methods, and the effect of annealing temperature on the formation of structures annealed at T = 350 °C, T = 450 °C, and T = 550 °C was investigated. The X-ray diffraction (XRD), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and field-emission electron microscopy (FESEM) were used to investigate the structural, optical, and surface morphological properties. The results obtained from the structural analysis of the synthesized samples showed that the SFO4 sample with the spinel phase synthesized by solvothermal had the highest intensity of the preferred peak (311) and a more uniform grain size. The FESEM images of the nanostructures showed cubic and polyhedral grains with cluster growth. The optical absorbance of the samples was studied using UV–Vis spectroscopy within the wavelength range of λ = 190–1100 nm. The highest absorption in the samples was related to SFO6, and the band gap showed an increasing trend with temperature in region Eg = 2.20–2.85 eV. The reason for the increase of band gap with increasing temperature is the formation of independent oxide phases in the nanoparticle's composition. The tin ferrite oxide spinel sample SFO4 showed a value of 2.53 eV. From the UV–Vis analysis, the values of refractive index (n), extinction coefficient (k), dielectric constant (ϵ ), Urbach energy (Eu) and reflection coefficient were studied. The results of the FTIR analysis in the fingerprint region confirm the vibrations caused by the presence of Sn–O and Fe–O metal oxides. The presence of metal oxide bonds indicates the formation of tin ferrite structure. [ABSTRACT FROM AUTHOR]