Gold coatings are widely used in many fields for their shining color, excellent corrosion resistance, and electrical conductivity. However, they are not mechanically strong with low wear resistance. In this paper, we have prepared nano-composite Au-Ni-TiO2 coatings by our newly developed sol-enhanced electroplating method. In order to obtain the optimal mechanical properties, a systematic study of Au-Ni-x TiO2 coatings with different sol concentrations (x is the sol doping concentration from 0 to 25 mmol/L) has been conducted. It was found that nano-particles (3-12 nm) of TiO2 were highly dispersed in the coating matrix. The mechanical properties of sol-enhanced nano-composite coating were significantly increased. The nano-hardness of the coatings was improved from 2.55 +/- 0.13 GPa to 3.20 +/- 0.15 GPa. Consequently, the scratch resistance and wear resistance of the sol-enhanced coating were also improved significantly. Meanwhile, the electrical resistivity of the sol-enhanced coatings keeps a same level as the pure Au-Ni coatings. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.