Activated carbon microtubes (CMTs) have been prepared from poplar catkins by chemical activation with ZnCl2. The as-synthesized porous CMTs have large inner tubes of several micrometers, large Brunauer-Emmett-Teller surface areas of up to 1400 m(2) g(-1), a complex porous structure with predominant micropores (>= 80 vol %), and small amount of mesopores (<= 20 vol %). Two-electrode supercapacitor cells constructed with the activated CMTs yield a specific capacitance of 206 F g(-1) and an energy density of 7.5 W h kg(-1) with aqueous electrolyte, values that are much higher than those of an activated carbon (160 F g(-1), 5.5 W h kg(-1)).