13 Thai coal deposits were studied for their suitable properties for activated carbon starting material. Ten of these deposits were found to be good to very good quality and consist mainly of maceral in huminite and liptinite groups, as well as low ash and sulphur. These deposits are : Na Hong, Mae Lai, Mae Tan, Ban Pu, Ban Hong, Ban Pa Kha, Bang Mark, Wai Lek, and Na Duang. They were tested by heating up at different temperatures, up to 850 degree celsius, and selected some of good performances to activated at laboratory scale. The products were tested and results were used as a criteria to design a pilot activated carbon plant from coal. The built pilot plant consists of a furnace with twin ovens, capacity 300 kg of raw coal 300. On top of the oven, sited a volatile carrier tube to the condenser, cyclone, and gas scrubber unit. The steam source was fitted in the draft system of the oven. After many times testing, using Mae Tan and Ban Pu coals, it was found the suitable conditions are : (1) to heat the coals until the volatile matter completely evolved, (2) sizing before activate with steam at 800 degree celsius for at lease 36 hr. The final products vary from 45-50 percent of the original mass with the Iodine Number of 630.