An electrophoretic process is proposed to deposit electrochemically-preformed Au or Pd NPs, with controlled size, directly on MWCNTs-based chemiresistors to improve the detection of aromatic pollutants, compared to pristine ones. The sensing properties of pristine and functionalized MWCNTs were evaluated at an operating temperature of 40°C towards various concentrations of one aromatic pollutant, belonging to the dangerous BTEX class of compounds, m-Xylene. The sensing performance was related to the metal used in the functionalization process. Metal-doped MWCNTs sensors exhibited a very high gas sensitivity to m-Xylene even at low (80 ppb) concentration at low operating temperature (40°C), good reversibility and repeatability, with the sensing properties controlled by the type of deposited metal catalyst. The results indicate that Metal-modified MWCNT-based chemiresistive gas sensors has good potential in practical applications, due to its remarkable performance, low power consumption, and facile synthesized methods. © 2017 Materials Research Society.