3D-Poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes are prepared using the multi-step template-assisted approach. Specifically, poly(lactic acid) nano- and microfibers collected on a previously polymerized PEDOT film are used as templates for PEDOT nano- and microtubes, respectively. Morphological analysis of the samples indicates that 3D-PEDOT electrodes obtained using a low density of templates, in which nano- and microtubes are clearly identified, exhibit higher porosity, and specific surface than conventional 2D-PEDOT electrodes. However, a pronounced leveling effect is observed when the density of templates is high. Thus, electrodes with microtubes still present a 3D-morphology but much less marked than those prepared using a low density of PLA microfibers, whereas the morphology of those with nanotubes is practically identical to that of films. Electrochemical studies prove that solid supercapacitors prepared using 3D-PEDOT electrodes and κ-carrageenan biohydrogel as electrolytic medium, exhibit higher ability to exchange charge reversibly and to storage charge than the analogues prepared with 2D-electrodes. Furthermore, solid devices prepared using 3D-electrodes and κ-carrageenan biohydrogel exhibit very similar specific capacitances that those obtained using the same electrodes and a liquid electrolyte (i.e., acetonitrile solution with 0.1 M LiClO4). These results prove that the success of 3D-PEDOT electrodes is independent of the electrolytic medium.