TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The catalyst used in step (d) comprises at least one bivalent nickel compound, at least one hydrocarbyl aluminum halide and at least one organic acid of Bronsted. The divalent nickel compound is divalent nickel salts of octoate group, ethyl-2-hexanoate, decanoate, stearate, oleate, salicylate and/or hydroxydecanoate. The hydrocarbyl aluminum halides are hydrocarbyl aluminum dihalides of formula (AlR1X2). The catalyst used in the second step of oligomerization (e) comprises at least one zeolite comprising ZSM-5 zeolite, NU-10 and/or ZBM-30.R1 = hydrocarbyl radical; andX = halo comprising F, Cl, Br or I.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: In the process, the entire olefin effluent produced during the step (d) of first oligomerization is directly sent to the step (e) of second oligomerization. The olefin effluent produced during the first step of (d) oligomerization undergoes at least one treating step of the homogeneous catalytic system and/or at least a separation step before sent in the second step (e) of oligomerization. The step of treating the homogeneous catalyst system is implemented by the use of capture mass or by treating olefin effluent obtained from the first step (d) of oligomerization, optionally neutralized and containing homogeneous catalyst system by an acid and/or base. The step of treating the homogeneous catalyst system is implemented by the separation of the olefin effluent obtained from the first step (d) of oligomerization, optionally neutralized by a base, of a first effluent comprising at least a part of more than 9C olefinic compounds and also the homogeneous catalyst system and a second olefin effluent free of the catalytic system, where the separation is followed by treatment of the effluent comprising at least a part of the more than 9C compounds and the homogeneous catalyst system by acid and/or base washing or by the use of capture mass. The separation step is implemented between the treatment step of homogeneous catalytic system and the second step of oligomerization (e), by separating the light olefin effluent obtained from the first oligomerization step (d) into at least one olefin effluent having greater than or equal to 4C and at least one 2-4C light olefin effluent. The entire 2-4C light olefin effluent is recycled in the first step of oligomerization (d). The step (e) operates at a temperature of 50-400 degrees C, at an absolute pressure of 2-15 MPa, and a weight hourly rate of 0.1-50 h-1. In the process, at least a part of middle distillates obtained from the fractionating step (f) undergoes a step of hydrogenation of olefins produced in the presence of a catalyst comprising at least one Group VIII metal comprising palladium and/or nickel, and a support comprising alumina, silica or silica-alumina. In the process, a separation step after the hydrogenation step is implemented to allow fractionating into a kerosene cut, gas oil cut and/or a cut having a boiling point of greater than 360 degrees C. Preferred Components: The Bronsted organic acid compounds are formed by halocarboxylic acids of formula (R2COOH).R2 = halo-2-10C alkyl containing at least one alpha halo of -COOH group. EXAMPLE - Bioethanol charge composition comprising ethanol (99 wt.%), methanol (less than 0.05 wt.%), butanol (less than 0.1 wt.%), other alcohols (less than 0.05 wt.%), total content of alcohol other than ethanol (less than 0.2 wt.%), oxygenated compounds other than alcohols (less than 0.1 wt.%), water (less than 1 wt.%), total cationic impurities (less than 0.005 wt.%), and total anionic impurities (less than 0.005 wt.%) was purified. The purified charge was dehydrated into ethylene and water in the presence of a zeolite catalyst (ZSM-5) at a temperature of 400 degrees C, at a pressure of 0.1 MPa and a weight hourly rate of 5 h-1 to obtain a dehydration product predominantly ethylenic hydrocarbon effluent comprising water. The effluent mainly ethylenic was then subjected to a series of separation and purification by passage through a column of water washing, then by passage through a column of washing with sodium hydroxide in dryers to separate a portion of the water formed the ethylene effluent. The separated effluent was sent in first oligomerization step, in the presence of a homogeneous catalyst comprising a compound of bivalent nickel and at a temperature of 45 degrees C and at a pressure of 3 MPa. The second oligomerization step was performed in the presence of the catalyst (powder of aluminum hydroxide mixed with a silica sol) and at a temperature of 150 degrees C, at an absolute pressure of 6 MPa and at a speed of 0.7 weight hourly rate of h-1. The effluent from the second oligomerization was subjected to fractionation to separate it into a light effluent comprising the 2-4C compounds, a gasoline cut and cut middle distillates (diesel and kerosene).