BACKGROUND Because of increasing environmental contaminations, hydrogen has attracted much attention as an effective and clean energy source. In addition, hydrogen and syngas are raw materials used in the production of valuable compounds. Methane dry reforming is one common method for syngas production. In this work, Ni catalysts supported on different ZnO-Al2O3 composite oxides were prepared. The effects of variation in Zn/Al ratio (Zn/Al = 0, 0.33, 0.5, 1, 2 and 3) on physico-chemical properties and their activity and stability in methane dry reforming were investigated. RESULTS The results indicated that Zn addition led to decreasing surface area, weakening the interaction between active phase and support, improving Ni reduction and therefore enhancing initial activity. CONCLUSION When Zn content was low or just enough to produce ZnAl2O4 phase, only metallic Ni particles were detected after reaction which led to carbon filaments formation and deactivation of catalysts. Increasing Zn content formed NiZn alloy that played essential roles in activity and stability. High amounts of Zn (Zn/Al = 3) did not favor promoting effects due to the increasing active phase sizes and decreasing contact area. Ni/ZnO-Al2O3 with Zn/Al = 2 exhibited the highest activity and stability in methane dry reforming. (c) 2018 Society of Chemical Industry