The surface-enhanced Raman scattering (SERS) spectra of size-separated polyynes C-2n-H-2 (n = 4-6) are reported via using gold nanoparticles as the SERS enhancer for the first time in colloids and poly(vinyl alcohol) films. The observed SERS bands show significantly improved signals and stability for at least 6 months in films. And the thermal stability of C8H2 is better than that of C10H2 and C12H2. The theoretical Raman modes of gold-capped polyynes are investigated by density functional theory. From the Au LIIII-edge X-ray absorption spectra, differences were found after adding polyynes to Au colloids or PVA films. (C) 2015 Elsevier B.V. All rights reserved.