A process for concurrently fractionating and hydrotreating a full range naphtha stream. The full boiling range naphtha stream is subjected to simultaneous hydrodesulfurization and splitting into a light boiling range naphtha and a heavy boiling range naphtha, which have been treated to convert mercaptans in the fractions to H.sub.2S, which is separated with and separated from the light naphtha which is further hydrodesulfurized by contacting the light boiling range naphtha with hydrogen in countercurrent flow in a fixed bed of hydrodesulfurization catalyst to remove recombinant mercaptans which are formed by the reverse reaction of H.sub.2S with olefins in the naphtha during the initial hydrodesulfurization wherein the improvement comprises fractionating said portion of light boiling range naphtha to remove a lighter fraction thereof from said countercurrent flow reactor before contact of said lighter fraction with said fixed bed catalyst, because the lighter fraction is substantially free of mercaptans and is not benefitted by further treatment.