In the present work, the MgO powder was prepared using a modified thermal/sol-gel method and used as catalyst for ozonation of pharmaceuticals contaminants. The effects of Mg source, alkaline agent, capping agent and calcination temperature were evaluated on the catalytic properties of MgO. It was found that MgO prepared with magnesium acetate as Mg source, NH4OH as alkaline agent, surfactant as capping agent, and calcination at 500 degrees C had the highest catalytic activity for acetaminophen (ACT) degradation. As-made MgO was a nanocrystalline nanoparticle with BET specific surface area of 257.3 m(2)/g and a high density of basic surface functional groups. The prepared catalyst had a high catalytic activity of 71.5% in degradation and of 62.8% in mineralization of ACT. Complete degradation and 94% mineralization of ACT attained in the MgO/O-3 process at the reaction times of 15 min and 30 min, respectively. Reaction with free center dot OH was the main mechanism involved in the ACT oxidation using the MgO/O-3 process. MgO could preserve its catalytic activity during the consecutive use in the process. Therefore, the MgO prepared using the novel method is an efficient and durable catalyst for ozonation of emerging water contaminants. (C) 2016 Elsevier B.V. All rights reserved.