In the present study, long staple lignocellulosic fibres were extracted from the arecanut leaf sheath, an agricultural biomass. The arecanut leaf sheath (ANLS) fibres have been extracted by alkali treatment. The important fibre properties such as fibre length, diameter, density, bundle strength, single fibre strength, moisture content and chemical composition are evaluated and compared with commonly available cellulosic fibres. Chemical nature and structure of ANLS fibre are determined using X-ray diffraction and FTIR techniques. The morphological structure and cross-section of the fibres were studied by scanning electron micrographs. The thermal properties of the fibre are characterized by thermo-gravimetric analysis. The potential of ANLS fibre to be used as a textile and reinforcing material is discussed in detail. © 2020 The Textile Institute.