Hybrid nanoparticles have been designed for second harmonic generation (SHG) activity and investigated individually using polarized nonlinear microscopy. The structure is based on the insertion of non-centrosymmetric conjugated organic molecules in a MnPS3 matrix which provides the ideal backbone for a one-dimensional alignment. The high efficiency of isolated nanoparticles in a polymer thin film and the investigation of SHG polarization responses indicate the existence of several mono-crystalline nano-domains within the same particle. The mean size of such particles is estimated around 90nm, which is further supported by Transmission Electron Microscopy. (c) 2006 Elsevier B.V. All rights reserved.