With polyvinylpyrrolidone (PVP) as fiber-forming agent and pore-forming template, the 3-dimensional (3D) porous thiolated organosilica fiber (PTOF) was fabricated by electrospinning PVP ethanol solution containing hydrolyzed Mercaptopropyltrimethoxysilane (MPTS) and colloidal Au followed by ethanol washing. With colloidal Au as seeds, Au nanoparticles (AuNPs) were successfully deposited on the surface of porous fibers in NH2OH/HAuCl4 solution. SEM, FTIR, XRD and CV characterization demonstrated the formation of AuNP-decorated porous organosilica fiber (Au-PTOF). The increased available active sites and conductivity of the Au-PTOF-modified electrode make it suitable as an ultrasensitive sensing platform for the detection of Hg (II), with a detection limit of 2.5 pM (S/N > 3). The high sensitivity and reproducibility demonstrate that the electrospun Au-PTOF is very promising for electrochemical sensing application. (C) 2014 Elsevier B.V. All rights reserved.