Coal tar pitch was chmically modified 10wt% benzoquinone(BQ) to raise the softening point of isotropic pitch pre-cursor and the precursor was melt-spun into fibers, stabilizd, carbonized and activated with steam at 900\'C. The weight loss of carbon fiber-benzoquinone (CF-BQ) increased with the increase of activation time like other fibers, but was lower than those of Kureha fiber at the same activation time in spite of larger geometric surface area.