The invention concerns the preparation of a catalyst comprising a support containing at least one oxide of the element Si, Al, Ti, Zr, Sn, Zn, Mg or Ln (where Ln is a rare earth), cobalt, at least one element A selected from the group formed by ruthenium, platinum, palladium and uranium, and at least one element B selected from the group formed by molybdenum and tungsten, characterized in that it comprises at least the following successive steps: (1) formation of a precursor comprising at least cobalt and at least a portion of the support; (2) at least partial reduction of the precursor in the presence of at least one reducing compound; and (3) deposition of any part of compound present in the catalyst and not present in the precursor on the reduced precursor. The invention also concerns the use of the catalyst in a process for the synthesis of C.sub.5.sup.+ hydrocarbons from synthesis gas.