Fischer-Tropsch synthesis (FTS) has been studied at 5 . 10(3) Pa, at 508 K, an H-2/CO = 2/1 molar ratio on Ru/gamma-Al2O3 catalysts (1% Ru wt./wt.), using Ru(AcAc)(3) (AcAc standing for acetylacetonate), RuCl3 and K(AcAc) as precursors; K/Ru and Cl/Ru molar ratios ranged from 0.14 to 2.18 and from 1.31 to 3.71, respectively. As Ru catalysts for FTS undergo easy alteration resulting from coke deposition, the results from kinetic runs were collected using both fresh catalysts (at 5-10 min time-on-stream) and also when steady state conditions were reached (about 150 min time-on-stream). The influence of K/Ru and Cl/Ru ratios on CO conversion and on the selectivity of the formation of different products in the reaction has been examined. Changes in activity, during the regeneration procedures of the catalysts, differ significantly when the precursor is Ru(AcAc)(3) (increase in activity after regeneration cycle) or RuCl3 (significant deactivation with a decrease in Ru surface concentration, as determined by XPS).