We observed phase shift in optical second harmonic generation (SHG) from interfaces of indium tin oxide (ITO)/copper phthalocyanine (CuPc) and ITO/pentacene. Phase correction due to Fresnel factors of the sample was taken into account. The phase of SHG electric field at the ITO/pentacene interface, eh interface with respect to the phase of SHG of bare substrate ITO was 160, while the interface of ITO/CuPc had a phase of 140 degrees. (C) 2014 Elsevier B.V. All rights reserved.