Three-phases chemical reactions are widely applied industrially. They are highly non-linear, multivariable, exothermal processes. The aim of the present work is to propose a dynamic model of an intensified continuous three-phases mini-reactor. This model is developed to enable the transient phase monitoring of the mini-reactor. The reactor is treated as an association of J stirred tank reactors in series with back mixing effect. The model is used to describe the dynamic behaviour of the reactor during the hydrogenation of o-cresol on Ni/SiO2 catalyst. The model consists in mass and energy balance equations for the catalyst particles, the gas and liquid bulk phases. The transient heat transfer between the metal body of the reactor, the coolant fluid and the bulk fluid are also taken into account.