PROCESS FOR CONVERTING A FEEDSTOCK OF ETHANOL AND HYDROCARBONS IN A FLUIDIZED CATALYTIC CRACKING UNIT, characterized in that it includes the following steps: a) dehydration of a stream of ethanol , which is introduced in a first reaction zone of an FCC reactor, in contact with a zeolite catalyst at contact time in the range 0.05 to 1.0 second, space velocity in the range 1000 to 4000h -1 , temperature in the range 530°C to 650°C, pressure in the range 200 to 400kPa, and catalyst/ethanol ratio in the range 10 to 100, obtaining a reaction medium which comprises the catalyst free of coke; b) introducing the preheated hydrocarbon stream into the reaction medium and cracking the hydrocarbons , in a second reaction zone of the FCC reactor, in contact with the catalyst which is dispersed in the reaction medium which leaves the first reaction zone, under conditions of temperature in the range 500°C to 620°C, contact time in the range 1.3 to 3.0 seconds, space velocity in the range 200 to 400 h -1 , and catalyst/hydrocarbon ratio in the range 5 to 20; c) separating a deactivated catalyst from hydrocarbon products, at the outlet of the reactor, at the end of the dehydration and cracking reaction; d)rectification of the deactivated catalyst to obtain a deactivated catalyst and to remove hydrocarbon products , which are then mixed with the hydrocarbon products from step c), to obtain streams of hydrocarbon products for the process e) regenerating the deactivated catalyst by combustion in the presence of air , resulting in combustion gases and a regenerated catalyst which return to the first reaction zone, wherein the ethanol correspond to a proportion of 0.15 to 50 wt% of the total feedstock, while the hydrocarbons are selected from fractions from petroleum refining with boiling points in the range 380°C to 600°C and the hydrocarbon products comprise fuel gas which contains hydrogen, C1, C2 and ethene, a light fraction of C3 and C4, naphtha high in aromatics going from C5 to hydrocarbons boiling up to 220°C, and other hydrocarbons boiling beyond 220°C and wherein said fuel gas comprises a proportion of ethene of 15 to 90 wt% of the stream of fuel gas. a) dehydration of a stream of ethanol , which is introduced in a first reaction zone of an FCC reactor, in contact with a zeolite catalyst at contact time in the range 0.05 to 1.0 second, space velocity in the range 1000 to 4000h -1 , temperature in the range 530°C to 650°C, pressure in the range 200 to 400kPa, and catalyst/ethanol ratio in the range 10 to 100, obtaining a reaction medium which comprises the catalyst free of coke; b) introducing the preheated hydrocarbon stream into the reaction medium and cracking the hydrocarbons , in a second reaction zone of the FCC reactor, in contact with the catalyst which is dispersed in the reaction medium which leaves the first reaction zone, under conditions of temperature in the range 500°C to 620°C, contact time in the range 1.3 to 3.0 seconds, space velocity in the range 200 to 400 h -1 , and catalyst/hydrocarbon ratio in the range 5 to 20; c) separating a deactivated catalyst from hydrocarbon products, at the outlet of the reactor, at the end of the dehydration and cracking reaction; d)rectification of the deactivated catalyst to obtain a deactivated catalyst and to remove hydrocarbon products , which are then mixed with the hydrocarbon products from step c), to obtain streams of hydrocarbon products for the process e) regenerating the deactivated catalyst by combustion in the presence of air , resulting in combustion gases and a regenerated catalyst which return to the first reaction zone, <EOS>