Beechwood shavings were activated with NaOH under N-2 to produce adsorbents with a microporous structure. An increase in impregnation ratio (0.5-3 g/g) resulted in much better development of pore vol. and surface area in adsorbents. The activation temp. (600-1000 degrees C) had a small influence. The soaking time (0.5-2 h) and heating rate (5-15 degrees C/min) did not play any significant role. The total pore vol. of the prepd. activated C achieved 1-1.2 cm(3)/g and spec. surface 2000-2700 m(2)/g as detd. by sorption of C6H6 and CO2 at 25 degrees C. The biomass used was a good raw material for prepn. of microporous activated C.