Water dispersible polypyrrole nanotube/silver nanoparticle hybrids (PPyNT-COOAgNP) were synthesized via a cation-exchange method. The approach involves the surface functionalization of PPyNTs with carboxylic acid groups (-COON), and cation-exchange with silver ions (Ag+) and followed by the reduction of metal ions. The morphology and optical properties of the produced PPyNT-COOAgNP nanohybrids were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectrometer, and UV-vis spectroscopy. The as-prepared PPyNT-COOAgNP nanohybrids exhibited well-defined response to the reduction of hydrogen peroxide, and as extremely suitable substrates for surface-enhanced Raman spectroscopy (SERS) with a high enhancement factor of 6.0 x 10(7), and enabling the detection of 10(-12) M Rhodamine 6G solution. (C) 2012 Elsevier Ltd. All rights reserved.