A flexible electronic substrate (FES) includes a metallic layer, a dielectric nanoceramic layer formed by oxidation of a surface of the metallic layer, and an electrical circuit formed on a surface of the dielectric layer. The FES may be used for supporting a device, for example a flexible display, an OLED, an optoelectronic device, or a rf device. The dielectric nanoceramic layer has a crystalline structure consisting of substantially equiaxed grains having an average grain size of 100 nanometres or less, a thickness of between 1 micrometre and 50 micrometres, a dielectric strength of greater than 20 KV mm−1, and a thermal conductivity of greater than 3 W/mK. The FES has a minimum bend radius of lower than 25 cm.