causing deterioration of strength properties of paper products. In addition, silica in the black liquor left from the alkaline pulping process causes problems during concentration of the liquor to be used as fuel. In many countries, burning of rice straw leads to serious environmental problems. Many studies have been conducted dealing with nano cellulose derived from rice straw as a source for cellulose fibers. Isolation of cellulose nano materials from rice straw and their use in novel bio nano composite having the potential to be used in different applications have been recently studied .HPC is an important thermoplastic, water-soluble and temperature-sensitive cellulose ether, which can be processed by virtually all fabrication methods used for plastics. HPC finds wide applications in the construction, medicine, food, daily chemical industry, and “smart” materials fields . Moreover, HPC films are characterized by excellent flexibility, low Tg at high humidity and being a barrier to oil and fat. Few studies dealt with improving properties of HPC by incorporation of nano cellulose. For example, incorporation of CNC into HPC matrix using a mixing/evaporation technique was carried out by Maet .The prepared cellulose nano composite membranes showed significant increase in the tensile strength and Young’s modulus at 5 wt% content of CNC when compared to neat HPC. The use of carboxymethylated nanofibrillated cellulose powder and TEMPO oxidized nanofibrillated cellulose as reinforcing fillers with HPC were also reported.The use of TEMPO-oxidized nanofibrillated cellulose in HPC an composites showed strong fibril-matrix interactions, as evidenced by remarkable storage modulus retention at high temperatures and a suppression of matrix glass transition at 5 wt% nanocellulose loadings . Oxidation by TEMPO converts the cellulose primary C6 hydroxyls on the CNC surfaces into the more polar carboxylic groups. Nano composite films based on HPC matrix and fibrillated oxidized cellulose were found to have superior mechanical properties when compared to those prepared non-modified CNC and MFC. The improvement in mechanical properties could be attributed to the higher H-bonding groups, dipole-dipole interaction, and Vander Waals forces between HPC and oxidized nano celluloses. The current work aims to investigate using of oxidized CNC(OXCNC) isolated from rice straw as reinforcing elements to improve tensile strength properties of HPC and decrease its water vapor permeability, and use HPC/OXCNC mixture as a coating for paper sheets made from bagasse pulp.