Objective & Background: Phenol and its derivatives are common organic pollutants existing in wastewater of many industries such as oil refineries, coal processing, coking operations, and petrochemical, resin, and plastic manufacturing industries. Phenol is very toxic for human and environment. Adsorption is one of the processes used to remove phenol from aqueous solution. At present, one of the most interested absorbents is agricultural wastes. Thus, the aim of this study was application of carbonized service bark (CSB) and modified-carbonized services bark by ZnO nanoparticles (ZnO/CSB) due to the abundance of these wastes in the area studied. Methods: This Applied fundamental study was performed in Batch system. The adsorbent was carbonized at 500 °C for 2 hours and soaking method was applied for their modification by ZnO nanoparticles. Required concentrations of phenol were prepared by dissolving crystalline phenol in double distilled water. All experiments were performed in 100 ml Erlenmeyer flasks on shaker and the effect of different parameters such as pH, contact time, adsorbent dosage, initial phenol concentration and mixing speeds were investigated. Phenol was measured by 4-aminoantipyrine colorimetric method according to standard methods for the examination of water and wastewater. Data were analyzed using Excel software. Results: Maximum removal of phenol was observed at pH 2 for both adsorbents. The best condition for both adsorbents obtained in initial phenol concentration of 50 mg/l, adsorbent dose of 1 g/l and mixing speed of 200 rpm. Conclusion: The results indicated that established ZnO on CSB may increase adsorption capacity and it can be used as an effective adsorbent for phenol removal.