Additive-free gold nanoparticles (AuNPs) were successfully synthesized by gamma ray irradiation in aqueous solution using HAuCl4 as precursor. The size was optimized by regulating the concentration of HAuCl4 and the dose of irradiation. The electrocatalytic performance of AuNPs for the oxidation of glucose was demonstrated. The obtained AuNPs displayed superior electrocatalysis for the oxidation of glucose with a linear response range from 50 mu M to 16 mM, and the limit of detection was estimated to be 14.2 mu M. The surface-enhanced Raman scattering (SERS) activity of the synthesized AuNPs was also investigated, which showed excellent SERS enhancement in the low concentration detection (1x10(-7) M) of Rhodamine 6G solution with an enhancement factor of 1.4 x 10(6). (c) 2014 The Electrochemical Society. All rights reserved.