Potential use of Chara contraria for sorption of Reactive Red (RR) 120 was investigated. The sorption process was highly dependent on various operating variables like particle size, adsorbent dose, pH, temperature, ionic strength, dye concentration, and contact time. Before and after the sorption of RR 120, adsorbent surfaces were characterized by FTIR-ATR spectroscopy. Equilibrium data was well predicted by Freundlich model. Kinetic sorption of RR 120 on C. contraria was well described by sigmoidal Logistic model. Activation parameters derived from Arrhenius and Eyring equations indicated that interaction was mainly physical sorption. Thermodynamic parameters showed that sorption process onto macro-alga was a spontaneous and endothermic nature. Low value of desorption suggested that both strong and weak binding forces could be present between dye and adsorbent. Overall, C. contraria, potentially low-cost adsorbent can be used for the removal of RR 120. (c) 2012 Elsevier B.V. All rights reserved.