Adsorption of a basic dye, Bismarck brown, from aqueous solutions onto acid activated corncobs was investigated. Various experiments were undertaken in a batch adsorption technique to study the effect of the process variables, which include initial pH, adsorbent dosage, initial dye concentration, particle size, temperature and agitation speed. The adsorption of Bismarck brown on to the adsorbent was found to improve with the increase in adsorbent dosage, finer the mesh size and at a neutral pH (value ranging from 6-8). It was observed that the adsorption was better with increasing temperatures and the process was endothermic with a H value of 35.698KJ/mole and the kinetics followed was first order in nature. The results showed that both Langmuir and Freundlich isotherms fit the equilibrium data. Also, the results revealed that activated carbon from corncob, a waste material, proved to be an excellent low-cost sorbent.