A novel hyper-branched alumoxane with dendritic structure (Alu-Den) was prepared via a polycondensation reaction between hydroxyl groups of boehmite and carboxylic groups of gallic acid for use as an adsorbent for elimination of cationic Methylene blue from aqueous media. The successful formation of tree-like structure of Alu-Den was confirmed by several analyses, including FTIR, XRD, FE-SEM, BET, DLS and TGA. Adsorption variables, such as adsorbent dosage and pH, were optimized to acquire the maximum efficiency for dye removal. The results indicated that 0.02 g Alu-Den can totally eliminate 10ml Methylene blue with concentration of 20mg/l at 288 K and pH=10. In case of visionary investigation, the sorption process conformed to the pseudo-second-order kinetic model for all prepared concentrations. The Langmuir, Freundlich and Sips isotherms were evaluated to define the interaction between dye molecules and dendritic alumoxane structures. The results showed that the empirical data were in agreement with the Sips isotherm. Additionally, the spontaneous and exothermic quiddity of Methylene blue adsorption onto Alu-Den surface was divulged by thermodynamics assessments. Eventually, the Alu-Den was regenerated following four time adsorption-desorption cycles without significant loss in adsorption capacity. Hence, owing to its biocompatibility, simply accessible precursors, and high recyclability, the present novel adsorbent offered superior potential for the elimination of cationic dyes from aqueous phase.