Nanoparticles of SnO2 have been prepared by co-precipitation method using SnCl2 as a precursor and subsequent heat-treatment at 600 C. X-ray diffraction (XRD) study reveals tetragonal structure of SnO2 nanopartcles without any secondary phase. Scanning electron microscopy (SEM) image shows the spherical grain morphology of SnO2 nanopaticles. In transmission electron microscopy (TEM) study of SnO2, particle size is found to be 25 nm, which is close to crystallite size (21 nm) from XRD using Scherrer equation. In Fourier transform infrared (FTIR) study, a broad peak centered around 650 cm-1 was observed due to Sn-O vibration. Frequency dependence dielectric anomaly is observed in SnO2 nanoparticles at low temperature. Capacitance and loss tangent are found to be decrease with increasing frequency and increase with increasing temperature.