Transformation behavior of carbonaceous species over a precipitated iron-based Fischer-Tropsch synthesis (FTS) catalyst was investigated by Mossbauer effect spectroscopy (MES), X-ray photoelectron spectroscopy (XPS), CO temperature-programmed desorption (CO-TPD), temperature-programmed hydrogenation (TPH), high resolution transmission electron microscopy (HRTEM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The catalytic activities were tested in a fixed bed reactor. It was found that during carburization the fresh catalyst was firstly reduced from alpha-Fe(2)O(3) to Fe(3)O(4), accompanied simultaneously with the formation of atomic (C(alpha)) and polymeric (C(beta)) carbonaceous species on the surface of the catalyst. With time on stream the Fe(3)O(4) formed in the near-surface regions was converted gradually to chi-Fe(5)C(2), and the amounts of C(alpha) and C(beta) species presented an increasing trend. Subsequently, these species were combined partly together to form the graphitic-type (C(delta)) carbonaceous species, and the C(delta) species largely covered on the surface of iron carbides. The formation of iron carbides (especially for chi-Fe(5)C(2)), C(alpha) and C(beta) species on the surface layers promoted the catalytic activity, whereas the C(delta) species formed restrained the active sites for FTS reaction. (C) 2011 Elsevier B.V. All rights reserved.