CO hydrogenation was investigated over Co or Fe catalysts supported on multiwall carbon nanotubes (MWNTs). Two types of catalysts were prepared. For the simple impregnation method, metal acetate precursors were deposited onto the surface of MWNTs. These catalysts were denoted as "I-samples." The second family of catalysts was prepared by deposition of preprepared metal oxide nanoparticles onto the MWNT support. These samples were labeled "P-samples." All of the samples were characterized by TPR and TEM measurements and tested in CO hydrogenation. TPR measurements showed easy reducibility of the metal ions in the I-Co and I-Fe samples. TEM images generally pointed to a rather uniform particle size both before and after the reaction. The highest catalytic activity and high selectivity toward C-2-C-4 and C5+ fractions, as well as for olefin formation, were found for I-Fe. Catalytic activity was lower for P-Co and P-Fe. It can be established that these novel catalyst systems have high activity with high olefin selectivity and high fractions of larger hydrocarbons. (c) 2006 Elsevier Inc. All rights reserved.