Defects generation in single-walled carbon nanotubes induced by soft X-rays from a synchrotron radiation source was investigated by in-situ C 1s soft X-ray absorption and recombination emission as well as ex-situ micro Raman scattering spectra. The spectral dependence of the defect generation efficiency shows that the illumination effect is resonantly enhanced in between the pi* and sigma* carbon 1s core absorption. A spectator Auger decay process is proposed as the most plausible mechanism for the defects generation. (C) 2009 Elsevier B.V. All rights reserved.