Production of 1,3-butadiene ethanol, that is more than 50% of the total weight of feedstock: A) conversion of feedstock and of ethanol effluent from separation B to a conversion effluent being a majority of 1,3-butadiene, water and ethylene, and to a hydrogen effluent, operating at a pressure between 0.1 and 1.0 MPa, a temperature between 300 and 500° C. in the presence of at least one catalyst; B) separation of conversion effluent originating from A and hydration effluent from C to an ethanol effluent, a butadiene effluent, a water effluent and an ethylene effluent; C) hydration of ethylene fed by ethylene effluent and/or water effluent both from separation B, to produce an ethanol hydration effluent then being recycled to separation B.