By using the electric field induced optical second harmonic generation (EFISHG) measurement, we studied the charging effects induced in double-layer ITO/polyimide (PI)/6,13-Bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene)/Au diodes. Fresh samples showed EFISHG response due to electrode charging and the Maxwell-Wagner type interfacial hole charging at the TIPS-pentacene/PI. On the other hand, aged samples showed the SHG response due to the electrode charging only. We concluded that using the EFISHG measurement is an effective way to probe degradation induced in organic devices. (C) 2011 Elsevier B.V. All rights reserved.