Catalysts derived from transition-metal-substituted hydrotalcite(Mg_6-xM_xAl₂(CO₃)(OH)₁₆•yH₂O; M: transition metal(Co, Cu, Mn, Ni or Zn), x: 0~6, y: 3~5) were investigated to find the best transition metal and x for partial oxidation of methane. Catalysts were characterized by XRD, SEM and TEM. Partial oxidation of methane was carried out by using 0.05 g of catalyst at a temperature range from 773~1073K. The CH₄/O₂ feed ratio was fixed to 2 (VHSV=120,000cm³/g h). The Ni-substituted catalyst showed the highest catalytic activity. The Co-substituted catalyst showed good catalytic activity at 1023K and above but its activity decreased rapidly at 973K and below. Other transition-metal-substituted catalysts showed poor catalytic activity. As the Ni/Mg ratio increased from 0.5/6 to 6/0, the differences in the catalytic activity and H₂ yield depending on the Ni/Mg ratio were not significant during a short-term test. In long-term tests, the catalyst with the Ni/Mg ratio of 3/3 showed the best catalytic activity and stability, and as the Ni/Mg ratio in the catalyst became higher from 4/2 to 6/0, the catalytic activity became lower and less stable.