Graphene shows fascinating applications in electrochemical methods and bionanotechnology, including drug assay, drug delivery, and DNA sensing. In this regard, we model the adsorption of organic compound on a reduced graphene oxide (RGO), using a first principles density functional theory-local density approximation method. The presence of functional groups and the exchange of nitrogen atoms with carbon atoms can significantly alter the overall magnitude of pi-pi interactions between the adsorbed molecules and RGO by giving rise to strong medium-range interactions involving it-orbitals of the substituents. In the next step, the data obtained from the modeling of the adsorbate on RGO, are coupled with electrochemical data obtained from the reduction of adsorbate, resulting in a logical electrochemical mechanism for the reduction of adsorbate on the electrode surface.