Nanocomposites of chitosan are produced using graphene sulphonic acid (SG) at five different compositions and are designated as SG0.5, SG0.75, SG1, SG3 and SG5; the numbers indicate weight percent of SG. The TEM & AFM micrographs indicate that the SG sheets are in exfoliated state. The thermal stability and the storage modulus of the composites increase with increasing SG concentration showing a maximum increase (202%) for SG5 sample. The stresses at break and Young's modulus have increased with increasing SG content. SG5 shows the highest increase of both tensile strength and Young's modulus of 290 +/- 7% and 200 +/- 7%, respectively. Analysis of the Young's modulus data suggests that SG sheets are randomly distributed and at >= 1 wt% concentration they are unidirectionally oriented parallel to the film. The system exhibits percolation threshold of 0.49 wt% SG and it attains maximum conductivity of 0.13 S m(-1) at 1.6 wt% SG. (C) 2012 Elsevier Ltd. All rights reserved.