Gold nanoparticles (Au NPs) were synthesized using Au containing CTAB gel as a precursor. The effect of concentration of NaBH4 on the structural, optical, catalytic and electrochemical properties of the Au NPs was also investigated. With the increase of NaBH4 concentration from 0.1 to 0.15 M, an increase in the particle size and change in the morphology from spherical to elliptical was observed. Absorption and emission properties of the Au NPs were also probed using UV–Vis and photoluminescence spectroscopy respectively. Synthesized Au NPs samples were explored as catalyst for the reduction of 4-nitrophenol to 4-aminophenol. Catalytic activity of Au NPs samples prepared using 0.1 and 0.15 M concentration of NaBH4 were also compared. It was found that Au NPs prepared using lower concentration of NaBH4 (Au-0.1) exhibits better catalytic activity compared to the other Au NPs sample (Au-0.15). Synthesized Au NPs were also utilized as electrode material for the detection of Pb2+ ions, results show that Au NPs modified glassy carbon electrode can detect very low concentration of Pb2+ ions (2 µM). Au-0.1 sample exhibited better electrochemical performance compared to the Au-0.15 sample. © 2015, Springer Science+Business Media New York.