In this study, a CuFe2O4 nanocomposite adsorbent was synthesized using the sol–gel method, and its application for removing Congo Red (CR) dye from aqueous solutions was investigated. Characterization showed agglomerated clusters with a porous, rough surface, containing carbon (23.47%), oxygen (44.31%), copper (10.21%), and iron (22.01%). A central composite design (CCD) optimized conditions. Maximum dye uptake occurred at pH 5.5, 125 mg/L concentration, and 3.5 g/L adsorbent dosage. Kinetics followed pseudo-second-order, indicating chemisorption, while isotherms fitted the Langmuir model (R2 = 0.9989) with maximum adsorption capacity 64.72 mg/g. Thermodynamics confirmed an endothermic, spontaneous, and feasible process. The CuFe2O4 adsorbent is promising for effluent treatment with excellent reusability. © 2024 Elsevier B.V., All rights reserved.