Electrochromic materials can change their optical properties reversibly for an applied potential due to electrochemical oxidation and reduction. Although the colour of the conductive polymer like polyaniline (PANI) can be controlled electrically, but its performance is still considered to be low due to the lack of conducting pathways at the nanoscale associated with random deposition morphology. Thus improvement can be achieved by incorporating with nanofillers namely carbon nanotubes that have excellent electrical conductivity, high surface area and good interconnectivity. PANI/CNTs films of various thicknesses with 2 mg of CNTs loading were produced and assembled into test cells for testing. It was observed that the test cell of PANI/CNT film with optimum thickness showed lower cut-off voltage for the changing of colour as the test cell of PANI film. This is attributed to better conductivity of the film due to the presence of CNT in the film. It is believed that uniform deposition of PANI/CNT film onto fluorine-doped tin oxide (FTO) coated glass electrode using better dispersion technique can further lower the cut-off voltage. In this work, electrochromic device has been developed in the portable form of test cell that allows for easy, safer, less hassle testing of electrochromic material. © 2012 American Institute of Physics.