In this study, a new supported catalyst (Co/OSAC) based on olive stones activated carbon (OSAC) was developed using the wetness impregnation method. A kinetic study was performed to investigate the effect of ozone/supported catalyst coupling process on nitrobenzene degradation in aqueous solution. Several analytical techniques, such as Nitrogen adsorption-desorption at 77 K, XRD, XPS and SEM-EDX analyses were used to characterize the new catalyst. The effect of adding t-BuOH as radical scavengers was also investigated. Characterization results showed that a highly distribution of cobalt nanoparticles on the surface of OSCA was obtained by using impregnation method. Results were modelled by a global first-order model (R-2 > 0.99). Co/OSAC exhibited a high activity in oxidation of NB compared to ozone alone and OSAC. The total organic carbon (TOC) removal proved that Co/AC/O-3 combined process increases significantly the mineralization of NB with about 65% in 20 min compared to 45% and 24% using O-3/OSAC and ozonation alone respectively. The kinetic contribution of radical mechanisms was estimated by using tertbutanol as radical scavenger. It was demonstrated that NB degradation is mainly due to radical generation promoted on the surface of the catalyst. (C) 2017 Elsevier B.V. All rights reserved.