A two-step chemical treatment of cotton fabric was performed with the attachment of fluorine moieties on hydroxyl group sites. The hydroxyl groups of cotton were initially acrylated by 2-isocyanaethyl methacrylate. Acrylic monomers, containing four to twelve fluorine atoms, had been used to build polymeric chain directly on the surface of cotton by means of radical polymerization. Fabrics became 10-20% stiffer and microscopy showed a clear change of the cotton surface after the treatment. Coated samples of cotton had shown hydrophobic property with a highest contact angle of 128 degrees. It was found that the increase of molecular weight of fluorinated polyacrylate on the cotton surface lowered contact angle value. The best results in hydrophobicity had been obtained at the molar stoichiometric ratio between the number of hydroxyl groups of cotton and the amount of fluorinated monomer added. This developed method allowed for the direct radical polymerization on cotton fabric, providing good hydrophobic properties with the formation of fluorinated polyacrylate of different molecular weights.