The paper reports the effect of chopping the vapour flow on properties of vacuum evaporated polyaniline thin films synthesized by aqueous polymerization pathway. The chopper was a metallic vane of V-shaped cut out placed between the substrate and boat in the path of evaporated vapour. It interrupted the flow of vapour at a constant rate. Fourier Transform Infra-red (FTIR) studies indicated that the vacuum evaporated films are more in reduced form and contain short chain oligomers. Improved adhesion and reduced intrinsic stress of polyaniline thin film due to chopping are obtained. Higher transmittance and lower refractive index films resulted due to the process of chopping as compared to the deposited films. Chopping also produces smoother surface morphology. (c) 2007 Published by Elsevier B. V.