As a biomass material, cotton was investigated for feasibility to be used as a cost-effective biosorbent for boron removal as the post-treatment in a desalination plant. Based on the batch tests, cotton demonstrated a good capacity of adsorption at a pH about 7. This capacity was found to increase with an increase of boron concentration; the maximum capacity is 11.3 mg/g. The linear Freundlich isotherm was rather the linear Langmuir isotherm. The semi-empirical of mono-parameter modeling with pH relation was developed in this study and experimental results and predicted data by the model are consistent.