The effect of a boron promoter (B/Co molar ratio of 0 - 0.2) on a Co-based catalyst in the dry reforming of methane (DRM) was investigated. All catalysts were characterized via X-ray diffraction, N-2-physisorption, transmission electron microscopy, CH4-thermogravimetric analysis (CH4-TGA), and X-ray photoelectron spectroscopy to evaluate the crystallinity, surface structure, morphology, coke deposition, and oxidation state. The DRM results showed that all catalysts exhibited similar catalytic performances except boron in high quantities. An appropriate loading of boron reduced the deactivation degree by over one or twofold for CO2 and CH4, respectively, compared to the boron-unpromoted catalyst. The boron-promoted catalyst showed a small weight increase compared to the unpromoted catalyst during CH4-TGA, indicating less coke deposition. The filamentous-type carbon species were detected on the boron-unpromoted catalyst after DRM, while filamentous carbon species were barely observed on the boron-promoted catalysts. Conclusively, boron promotion influences the deactivation degree by suppressing coke deposition. [GRAPHICS] .