The unique property of gold nanoparticles (Au NP) to induce colour change and the versatility of graphene oxides (GO) in surface modification makes them ideal in the application of colorimetric biosensor. Thus we developed a label free optical method to detect DNA hybridization through a visually observed colour change. The Au NP is conjugated to a DNA probe and is allowed to hybridize with the DNA target to the GO thus causing a change in colour from pinkish-red to purplish blue. Spectrophometry analysis gave a wavelength shift of 22nm with 1µM of DNA target. Sensitivity testing using serially diluted DNA conjugated GO showed that the optimum detection was at 63nM of DNA target with the limit at 8nM. This proves the possibility for the detection of DNA hybridization through the use of dual nanoparticle system by visual observation.