Pore structure in nanometric scale in carbon spheres prepared from resol-type phenol resin was controlled by air oxidation. The yield values of oxidation at different temperatures were able to be superimposed by shifting along the axis of logarithmic residence time and to get a master curve at a reference temperature 400degreesC, a linear dependence of shift factors on the reciprocal absolute temperature of oxidation giving apparent activation energy of 200 kJ/mole. Based on the conversion between oxidation temperature and time, all experimental data of the pore parameters could be converted to the values at 400degreesC. Total pore volume increased with increasing in residence time at 400degreesC up to 40 h, but tended to reduce by further oxidation gradually.