Improved gluten materials were prepared using bio-fermentation and acid bath coagulation methods for congo red adsorption. After comparison, the method of acid bath coagulation with better effect was selected and further preparations of improved gluten materials were achieved under different acid coagulation baths and the solid-liquid ratios. Finally, particular adsorption properties were studied using the sample of improved gluten material with the acid coagulation bath of HCl and the solid-liquid ratio of 1:5. Influence parameters on the congo red adsorption such as temperature, dose, contact time and pH were discussed. The adsorption properties of the improved gluten material were investigated by isotherm (the Langmuir model and the Freundlich model), kinetics (the pseudo-first-order, pseudo-second-order and intra-particle diffusion equations) and thermodynamic analysis. The results showed that this improved gluten material was an efficient adsorbent for removal of congo red. (C) 2019 Elsevier Inc. All rights reserved.