The present work describes the interaction between biopolymer chitosan and mercaptobenzimidazole (MBI) for the adsorption of palladium. The effective coordination with palladium occurs through a secondary host-guest interaction. The probable adsorption mechanism could be understood through FT-IR, SEM, EDX and XRD techniques. The pH of aqueous medium and the adsorbent dosage were optimized through batch adsorption studies. Adsorption kinetics, isotherm models and thermodynamic parameters were utilized in validating the experimental adsorption data. The spontaneity, exothermicity and decreased randomness at the solid-solution interface were also confirmed through the thermodynamic data. The chitosan-MBI adsorbent could be regenerated and reused for 3 cycles using thiourea. (C) 2014 Elsevier B.V. All rights reserved.