Macroscopic carbon fiber (CF) sponges were synthesized using a one-step chemical vapor deposition (CVD) method at 230 degrees C. The CF sponges can grow large in a single run and the yield reaches up to 2854% in 1 h without any additive. The CF sponges were self-assembled into a porous three-dimensional framework and the length of a single fiber is more than 10 mu m.