i) continuously feeding ethylbenzene and/or ethane to at least one reaction vessel, suited for carrying out a catalytic dehydrogenation reaction, comprising a catalyst and operating under fluid conditions;

ii) discharging a reaction product from a head of the at least one reaction vessel, sending the reaction product to a subsequent separation, recovering and recycling of non-reacted components;

iii) continuously removing a stream of exhausted catalyst from a lower portion of the at least one reaction vessel and, after stripping with an inert gas to remove interparticle gas, regenerating and heating the catalyst in a fast riser regenerator, using regenerating gas as carrier in equicurrent with the catalyst;

iv) continuously removing a stream of regenerated and heated catalyst from the head of the fast riser regenerator and, after optional stripping with inert gas, feeding the regenerated and heated catalyst to an upper part of the dehydrogenation reactor using a reagent gas, or ethane in the case of ethylbenzene/ethane mixture, as carrier;

wherein a residence time of the catalyst in the fast-riser regenerator is less than 30 seconds.