SnO2 nanoparticles were synthesized by co-precipitation technique. The synthesized SnO2 nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-visible diffused reflectance spectrometer (DRS). The XRD results addressed that the SnO2 nanoparticles was crystallized in rutile tetragonal structure. The SEM analysis confirms that the prepared nanopowder is composed of nanoparticles. Analysis of the DRS UV-Vis spectrum showed that the band gap of the synthesized SnO2 is to be ∼3.4 eV. The small cladding portion of the optical fiber was replaced with the synthesized nanoparticles. The ammonia sensing characteristics of the prepared SnO2 nanoparticles were analyzed for different wavelength ranges (red, yellow and blue) using polymethyl methacrylate fiber. It has been found that the synthesized SnO2 nanoparticles shows high sensitivity (∼23) in yellow wavelength range compared with red and blue wavelength ranges at room temperature. © 2018 Institute of Physics Publishing. All rights reserved.