A goal of this work was to investigate the influence of the preparation procedure and activation conditions (reduction temperature and reducing medium: pure hydrogen (100% H 2) or hydrogen-argon mixture (5% H 2-95% Ar)) on the activity of Co-containing BEA zeolites in Fischer-Tropsch synthesis. Therefore, a series of CoBEA zeolites were obtained by a conventional wet impregnation (Co 5.0 AlBEA) and a two-step postsynthesis preparation procedure involving dealumination and impregnation steps (Co 5.0 SiBEA). Both types of zeolites were calcined in air at 500 • C for 3 h and then reduced at 500, 800 and 900 • C for 1 h in 100 % H 2 and in 5% H 2-95% Ar mixture flow. The obtained Red-C-Co 5.0 AlBEA and Red-C-Co 5.0 SiBEA catalysts with various physicochemical properties were tested in Fischer-Tropsch reaction. Among the studied catalysts, Red-C-Co 5.0 SiBEA reduced at 500 • C in pure hydrogen was the most active, presenting selectivity to liquid products of 91% containing mainly C 7-C 16 n-alkanes and isoalkanes as well as small amount of olefins, with CO conversion of about 11%. The Red-C-Co 5.0 AlBEA catalysts were not active in the Fischer-Tropsch synthesis. It showed that removal of aluminum from the BEA zeolite in the first step of postsynthesis preparation procedure played a key role in the preparation of efficient catalysts for Fischer-Tropsch synthesis. An increase of the reduction temperature from 500 to 800 and 900 • C resulted in two times lower CO conversion and a drop of the selectivity towards liquid products (up to 62%-88%). The identified main liquid products were n-alkanes and isoalkanes. The higher activity of Red-C-Co 5.0 SiBEA catalysts can be assigned to good dispersion of cobalt nanoparticles and thus a smaller cobalt nanoparticles size than in the case of Red-C-Co 5.0 AlBEA catalyst.