This study's objective was to develop a model to determine dye adsorption efficiency of Treptacantha barbata (Stackhouse) Orellana& Sansón, 2019 (formerly Cystoseira barbata (Stackhouse) C. Agardh, 1820). During the experiments, treatment groups, such as initial dye Methylene Blue (MB) concentration (0.1-10.0 mg L-1), contact time (5 to 1440 min) and adsorbent dosage (0.1-2 g) were applied. Scanning electron microscopy, energy dispersive X-ray, and Fourier Transform Infrared Spectroscopy were used to analyze the adsorbent. T. barbata was found to be quite successful in removing dye (69% -100%) for all experiments, and the qe values increased with the increased the initial dye concentration. Very rapid dye removal was detected during the first contact time, especially up to 15 min. Isotherms, kinetics, and regression models were applied to the batch experimental results. The results displayed that adsorption process was suitable with the Langmuir isotherm model (R2: 0.97).