The properties of amorphous poly(o-toluidine)/magnesium oxide (POT/MgO) nanocomposite films with different thicknesses (t= 107, 191, and 309 nm) deposited via chemical polymerization onto glass substrates at 0°C were investigated. FE-SEM images revealed that POT/MgO thin films have nanorod structures with diameters in the range of 93.13-204.65 nm. The increase in the thickness leads to an increase in the nanorod diameters. The samples were characterized through fourier transform infrared spectroscopy to examine the effect of the increase in the thickness on the functional group of POT/MgO nanocomposite thin films. X-ray diffraction showed that the POT/MgO thin films have an amorphous structure. Conductivity measurements indicated that conductivity is 3.85 S.cm−1 at 309 nm film thickness, increases to 6.98 S.cm−1 when thickness decreases to a nano range.