Abstarct: In this work, pure and boron doped tin oxide nanoparticles were synthesized by sol-gel rout. Then structural properties and gas sensing performance of the samples were investigated. For characterization, we used the Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD), I-V measurement apparatus and Gas Sensing Reactor. XRD patterns confirmed the formation of the rutile structure for all samples. The results showed that the crystallites size of the doped sample was decreased compared to the pure sample. The average crystallite sizes were in the range of 7-13 nm. FESEM images demonstrated that all samples consist of quasi-spherical shap grains with nano-scale size and have high porosity. The results of gas sensing performance investigation of the samples showed that the sensitivity is highest value for sample with 2 wt% boron and their values are 95% and 86% to ethanol and methanol, respectively. For this sample, the optimum operating temperature in the presence of ethanol and methanol were 190 °C and 250 °C, respectively.