This paper describes the response to moisture absorption and some mechanical properties of jute fibres (Corchorus capsularis) on dewaxing, delignification, bleaching and treatment with jute batch oil-in-emulsion. On dewaxing the dimension of the capillaries expand from 100 Angstrom for raw fibres to 107 Angstrom. On scouring with detergent, the capillaries contract slightly. On treatment with jute batch (JB) oil-in-emulsion the dimension of the capillaries contract to 92 Angstrom and the angle of contact increases, and the combined effect of these factors is a reduction in moisture absorption. On delignification and bleaching the capillaries contract in diameter and the angles of contact increase with respect to the dewaxed fibres. Moisture absorption decreases on delignification and bleaching suggesting that moisture absorption takes place in the amorphous region of the fibres. The diffusion coefficient for raw fibre was 3.37 x 10(-13) m(2) s(-1) which decreases on delignification, bleaching and washing with soap. Also Young’s moduli decrease on removal of lignin and hemicellulose, showing their cementing role. Tensile strength at yield for raw and JB oil treated fibres are 318 and 418 MPa respectively. On delignification, bleaching and washing with nonionic soap tensile strength decreases considerably. The strain % at break increases from 5.0 for raw jute fibres to 37.0 far fibres treated with JB oil-in-emulsion; and the elastic energy increases from 0.05 J for raw jute fibres to 1.98 J for JB oil treated fibres. Breaking toughness for raw jute fibres is 13.4 MJ m(-3) and this reduces to very much lower values on delignification, bleaching and washing with non-ionic soap. On treatment with JB oil-in-emulsion the breaking toughness increases to 80.0 MJ m(-3).