The ease of cultivation, structure and properties of hemp (Cannabis sativa L.), provide it a great potential for industrial applications; nevertheless, the unfavourable high content of lignin complicates its processing, especially in the textile area. An appropriate knowledge of the delignification process would lead to treat hemp fibres as cotton fibres. In this work, hemp has been treated chemically with an alkaline bath with sodium hydroxide [1M], liquor ratio 1/15, during different times at 110 °C. Then, the content of lignin of the treated fibres was determined with the methodology of Tappi T222 om-15 standard and subsequently, the samples were analysed by thermogravimetry (TGA). Through the correlation analysis, the relationship between lignin content, onset temperature of cellulose decomposition and loss of mass of the different decomposition steps were found. Finally, the kinetics of alkaline hemp delignification by using the residual lignin after chemical treatments, and the kinetics of the different decomposition steps was determined