Surface functionalization of diamond with amine groups and immobilization of gold nanoparticles (AuNPs) on boron doped nanocrystalline diamond (BDND) films deposited by microwave plasma chemical vapor deposition were investigated. Hydrogen-terminated BDND film surfaces were activated through bonding with allylamine molecules under UV light irradiation. The resulting diamond surfaces were characterized by using X-ray photoelectron spectroscopy and water contact angle measurement. The amine groups were successfully bonded covalently on the BDND diamond surface via a direct photochemical reaction with allylamine. Gold nanoparticles with the average size of 15 nm were then further self-assembled on the amine-terminated diamond surface by immersing the film surface into the gold colloidal solution, and a dense and well distributed AuNPs array in two dimensions with controlled density was obtained. Standard Rhodamine 6G probe molecules were used to access the surface enhanced Raman scattering (SERS) activity of the prepared new SERS substrate based on AuNPs modified BDND film. The results indicated that such AuNPs modified BDND film showed an excellent and stable SERS activity in the low concentration detection of R6G due to the electromagnetic enhancement mechanism. (C) 2013 Elsevier B.V. All rights reserved.