Carbon nanotube based chemical sensors have recently attracted a great deal of attention because of their superior sensing performance, due to their high surface area to volume ratio and unique physical properties. Nevertheless, several issues still remain. First, imparting selectivity to nanotube sensors and second to modify SWNT sensors for detecting low molecular weight gases like methane, hydrogen etc. In this present work we tried to address the above issues. The physical properties of single walled carbon nanotubes can be significantly altered by selected coating with organic and inorganic species. Here we demonstrate site specific electrochemical functionalization of single-walled carbon nanotube (SWNT) with metal oxides (e.g. SnO2). Tinoxide with its wide energy gap (~3.6 eV) is an important metal-oxide semiconductor. It has many important applications in the transparent conducting coating of glass, electrochemical modifiers on electrodes, solar cells, and gas-sensing devices. As both tinoxide with its wide energy gap and SWNT with its high surface area can play significant role as molecular detection and transduction systems, coating of SWNTs with such metal oxides might have a synergistic effect in chemical sensing applications. In the present work tinoxide coated SWNTs was used for detecting combustible gases (e.g. methane, ethylene) and for nerve agent simulants (e.g. dimethyl methyl phosphonate (DMMP), Di-Butyl sulfide). Tin oxide microstructures on SWNTs were characterized by X-ray diffraction, atomic force microscopy, Raman spectroscopy, FT-IR and scanning electron microscopy.