Adsorption property of graphene oxide (GO) towards cationic dyes such as methylene blue (MB) and rhodamine B (RhB) has been investigated experimentally. GO structure used in our study is decorated with experimentally observed oxygen functional groups (OFGs). Fast and effective adsorption of MB with GO in single and binary solute solution has been observed experimentally. In support of our experimental data and to understand the interaction of adsorbent (GO) and dye, density functional theory (DFT) calculation has been used for calculating individual binding energy of GO, GO/dye in aqueous medium. Further, study on dye interaction with GO reveals that adsorption was facilitated by presence of oxygen functional group through electrostatic interactions.