In this paper, we re-assess the use of Raman spectroscopy as an in situ method to monitor the sulfidation of SOFC (solid oxide fuel cell) anode-based materials. The technique allows studying in situ kinetics of the sulfidation of nickel at low temperature (up to 500 degrees C). A severe poisoning happens at 500 degrees C with a layer of Ni3S2 covering the entire pellet surface. At higher temperatures, optical microscopy helps to observe in situ the formation and growth of nickel sulfide crystals for the first time. The crystals' growths observed in situ strongly suggest the diffusion of nickel toward sulfide species. A reaction between H2S and CGO was clearly observed at 750-790 degrees C. (C) 2015 Elsevier B.V. All rights reserved.