Through molecular and solid-state approaches, structural and electronic properties of graphene oxide (GO) using substitutional doping were studied. Nitrogen, boron, phosphorus, silicon, aluminum, arsenic, and germanium atoms were integrated to GO at various sites to search for a suitable candidate that can reduce the energy gap of GO. As per our molecular investigations, Si- and Ge-doped GO reduces nearly 10% of the gap compared to the undoped molecule, while P, As, and N doping enhance the gap more than 50%. B and mainly Al (more energetically favorable structures) were found to be a suitable choice to be doped in GO, as it causes up to a 60% reduction in the energy gap compared to that of pristine GO. Moreover, the periodic calculations revealed that the introduction of Al can turn the GO structure into a metallic one. In addition, our studies disclosed that not only the dopant type but also the dopant sites are crucial in order to alter the electronic properties of GO.