Optimized process for effecting the production of heavy hydrocarbons according to the Fischer-Tropsch method which comprises: (a) feeding the reagent gases into a reactor; (b) at least partially recovering the heavy hydrocarbons formed in step (a) by their external or internal separation from the catalytic particles; the above process being characterized in that in step (a) the reaction takes place: (1) in t he presence of solid particles which have a particle Reynolds number (Rep) greater than 0.1, (2) keeping the solid particles suspended at a height H, with Us, Ul, and Ug value s which are such as to have a Bodenstein number Bos≦1, preferably ≦0.4.