A coupling device for a hybrid power plant operates in at least two electrical/internal-combustion-electrical modes designed for a vehicle, whereby the coupling device includes a first drive shaft that is coupled to an electric motor and a second drive shaft that is coupled to an internal combustion engine. The coupling device includes at least one primary shaft that can be coupled by first or second transmission element to the first or the second drive shaft under the action of selection element that can assume a first position and a second position in such a way that: In the first position of the selection element, the primary shaft is coupled to the first or to the second drive shaft by the first or the second transmission element; and In the second position of the selection element, the primary shaft is coupled to the first drive shaft by the first transmission element.