The efficient removal of various dyes from the waste waters of textile industries is an important and challenging task. In the present study, it is attempted to validate the applicability of a new nanocomposite adsorbent for the removal of a cationic dye Rhodamine B from the effluent wastewaters. Magnesium oxide nano particles are encapsulated on a low cost activated carbon prepared from delonix regia and used for sorption study. The nano composite is characterized using FTIR, SEM, TEM, XRD, EDAX and BET. The effect of parameters like adsorbent dosage, contact time, pH, adsorption capacity and desorption have been studied. The adsorption studies indicate that Langmuir and Temkin isotherms are found to be the apt models due to their higher correlation coefficients. It fits well with pseudo first order kinetics having good agreement with the experimental values.