In this paper, the high chemical activity of the newly synthesized nanosize carbon spheres is demonstrated. The carbon spheres can be accreted by a treatment in acetone, The mechanism for the accretion is attributed to the combination of the hydrogen and oxygen atoms belonging to the acetone molecules with the adsorbed hydrogen and/or oxygen atoms at the edges of the open graphitic flakes distributed at the surface of the carbon spheres. The high chemical activity of the carbon spheres can have important applications in catalysis. The accretion of the carbon spheres may significantly improve the strength of composite materials made using the spheres.