In present work, the H2O/CH4 on carbon deposition in SRM reaction over Ni/ZrO2 was studied. Prepared by impregnation, the catalysts were characterized by TEM, XPS, H-2-TPR, TG-DSC-MS, Raman, and XRD. The results showed that when H2O/CH4 = 2 with GHSV of 14460 h(-1), the highest CH4 conversion (46.8%) was achieved on the Ni/ZrO2 catalyst at 550 degrees C. This was due to the relatively high surface content of Ni-0 (27%) species and the formation of easy removal polymer carbon (C-1). When the H2O/CH4 was 1, a large amount of difficult to remove fiber carbon (C-2) formed and polymer carbon would wrap around the catalyst to reduce its activity. However, excess water might promote surface reconstruction by converting Ni-0 to Ni(OH)(2), which reduced the surface Ni-0 content and then inhibited the catalytic activity, while the amount of carbon deposited, especially C-2, reduced significantly. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.