Abstract Cross flow ultrafiltration (UF) using a cellulose membrane (cut off of 5 kDa) was employed to separate phenolic compounds from carbohydrates of hydro-ethanolic extract obtained from Zizyphus lotus fruit. The performance of the UF membrane was evaluated in terms of permeate flux, fouling index and retention values of total phenolic compounds, carbohydrates and uronic acid contents. The results showed that at VRF of 4.5, the membrane gave the highest rejections towards carbohydrates (99.89 %) and uronic acids (82.8 %) and the lowest average rejection of total phenolic compounds (3.12 %). Moreover, the permeate fraction exhibited the highest 2,2-diphenyl-1-picrylhydrazyl free radical scavenging ability and total antioxidant capacity with 0.036 mg.mL⁻¹ and 102.145(mgGAE.g⁻¹DM), respectively. This result is due to the presence of phenolic compounds (gallic acid, syringic acid, catechin, quercetin and kaempferol) as identified by HPLC system. Besides, a low rejection values of the UF membrane concerning these compounds were confirmed by liquid chromatography analyses.