This study focuses on producing SnO2 nanoparticles using environmentally friendly methods (green method) with the help of Portulaca oleracea (P.O) extract work as a reducing and protecting agent instead of using chemical materials. Afterward, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and the X-ray diffraction pattern were used to infer the grain size and crystal structure. The band gap energy of (4.2 eV) was determined using the UV–V is spectrum; this redshift in comparison with (3.6 eV) bulk SnO2 may be due to the quantum effect. The mefenamic acid (MFA) in aqueous solutions was used to examine the adsorption behavior of SnO2 nano crystals. To identify the optimal adsorption circumstances, a number of variables were examined, including pH, MFA concentration, temperature, studying duration, and adsorbent dose. It was discovered that when the MFA concentration and SnO2. P.O dosage were 30 mg/L and 0.6 g, respectively, within 30 min, the maximum removal efficiency was 97%. The MFA adsorption mechanism is consistent with the Freundlich isotherm models.