One-dimensional nanostructures 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. We demonstrated a facile fabrication method to synthesize chemical gas sensors using electrochemically functionalized single-walled carbon nanotube (SWNT) with metal nanoparticles (e.g. Pd) and metal oxide nanoparticles (e.g. SnO2). The potential advantage of this method is to enable targeted functionalization with different materials to allow for creation of high-density individually addressable nanosensor arrays. For examples, Pd nanoparticles were electrodeposited on SWNT networks to create a hydrogen gas sensor. By varying deposition conditions (e.g. deposition time, electrolyte composition, and resistance of device), the sensing performance were systematically optimized. The optimized sensor showed a superior sensitivity toward hydrogen (~0.424 % R/R / ppm ) with a good linear response and detection limit of 100 ppm. The response and recovery times were in the order of minutes. In addition to palladium, SnO2 nanoparticles were also electrodeposited on SWNTs to detect volatile organic compounds (VOCs). Systematic investigations on the effects of selected parameters on the sensor characteristics allowed to develop a better fundamental understanding of the sensors. The latest results will be presented and discussed at the conference.