Activated carbon was manufactured from the mixture of anthracite and bituminous coals from China under various experimental conditions using steam as the activation agent in a batch type rotary kiln. The effects of coal size and the weight ratio of anthracite and bituminous coals on the properties of activated carbon have been determined. The nonisothermal kinetic model was employed to determine the activation energy of the steam-anthracite and bituminous coals and the resulting values are 6.25 and 15.57 kcal/mol, respectively. The carbonization temperature do not produce any significant effect on the properties of activated carbon, whereas carbonization time affects the pore structure of activated carbon due to the mild gasification. The range of micro pores increases with increasing reaction time at a given temperarture, but the adsorption capacity, porosity of activated carbon decrease and the average pore diameter decrease with increasing reaction temperature at a given reaction time. The content of anthracite do not affect the adsorption capacity of iodine(I₂)and methylene blue(MB), but it increased micro pores. With the coal size of 0.1mm, volatile material in the coal was evaporated explosively in the carbonization process so that non-uniform pore were produced. However, the effect of coal size less than 0.075mm on the pore structure is founded to be marginal.