X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), UV-visible spectroscopy, and the Kubelka-Munk transformation were utilized to measure the absorption curves and the band gap in the pure and Ce-doped SnO2 nanoparticles that were synthesized using a sonochemical technique. Using the Dielectric LCR meter, all electrical characteristics, such as impedance, ac conductivity, dielectric constant, and dielectric loss, were measured at room temperature. Methylene blue photodegradation was used to evaluate the photocatalytic performance. Cerium (Ce) at varying concentrations was introduced to SnO2 nanoparticles in order to broaden the optical absorption spectrum and extend into the visible spectrum. The Debye-Scherrer equation was used to determine the average crystallite size of the undoped and Ce-doped SnO2 NPs, and the results showed that the nanoparticles are in the tetragonal rutile SnO2 phase. The band gap and absorption peak of the SnO2 and Ce-doped SnO2 NPs were determined using the UV-visible absorption spectra. The presence of increasing concentration of Ce, in an excess of 0.5% (w/w), is found to shift the absorption edge towards higher wavelengths and the band gap energy drops from 3.620 to 3.031 eV. The FTIR spectrum revealed the stretching of the vibration bond in a certain frequency range is shown by the O-Sn-O bond information. The SEM images showed the formation of nearly spherical nanoparticles. Ce-doped SnO2 NPs have smaller primary particles than SnO2 NPs. The UV-Vis spectra showed the reduction in band gap due to increase in defects by doping Ce content. The existence of Sn and O elements was confirmed by the observed EDS spectra. Methylene blue was broken down under UV light irradiation in order to examine the photocatalytic activity of SnO2 and Ce-doped SnO2 NP photocatalyst and observed that Ce-doped SnO2 NPs demonstrate improved photocatalytic activity as compared to SnO2. The influence of Ce concentration doping on the electrical properties was observed at room temperature. Impedance decreases with frequency and Ce concentration while ac conductivity is observed to increase with frequency and Ce concentration. Dielectric constant and dielectric loss rise with Ce doping and decrease with frequency. Therefore Ce-doped SnO2 showed improved ability of photo degradation and the optimal ability of SnO2 nanoparticles was achieved by 0.5 at% Ce doping.