There is a great global interest in controlling air pollutants, specifically greenhouse gases including nitrogen oxides (NOx), nitric oxide is one of its basic components. For this reason, this study dealt with the use of biochar manufactured from agricultural waste from sunflower seed husk (SSHB) with 450oC pyrolysis in the adsorption of 90 ppm concentration of nitric oxide (NO) gas within 480 seconds (8 minutes) by flow rate 1.2 (liter/minute). Two kinds of particle sizes coarse (C) and fine (F) of SSHB were used, and some physiochemical properties of the biochar were studied, including SEM and FTIR, in addition to the BET surface area, which was 3.9 (m2/g). The adsorption results displayed that SSHB (F) is better at the adsorption of NO 31.6 (mg/g) than SSHB (C) 26.7 (mg/g). Isotherm models were applied to the mathematical modelling of NO absorption, and based on n and R2 values the results of the SSHB adsorption for NO fixed with both the Freundlich model and the kinetic pseudo second order model.