The pyrolysis of D152 and the steam activation of Ni– Ca/C were significantly accelerated by the catalysis of doped nickel and calcium. The major thermal decomposi- tion and carbonization of D152 occurred between 380 C and 520 C. The reduction of nickel ion to metallic nickel and the formation of CaCO3 from Ca(OH)2 and CO2 took place in the carbonization process at 500 C and below. The mechanism of carbonization of Ni–Ca/D152 should include metals catalyzed dehydration, decarboxylation, cyclization, crosslinking, decomposition and structure rear- rangement of Ni–Ca/D152, reduction of Ni2+ to metal by carbonaceous products, formation of CaCO3 from Ca(II) and CO2 under 500 C, and precipitate of graphite.