<p>The need for advanced components for electronic systems is intensively researched in the past years. This work is devoted to the preparation of innovative materials based on biodegradable polymer and bio-derived conductive particles with potential use as flexible capacitors or semiconductors. Structural characteristics of the pure components and composites are investigated by energy dispersive X-ray spectroscopy and infrared spectroscopy. The filling of the cellulose ether matrix with nettle leaf ash produces microstructural changes that are reflected in the rheological, morphological, optical and electrical properties. Thermal analysis indicates that the glass transition is shifted to higher temperatures upon the filler incorporation in the polymer. Tensile tests show that the filler diminishes the tensile stress at tearing, while the maximum elongation experienced by the samples at rupture is slightly enhanced. The performed analyses reveal a transition (by the gradual loading) from individual conductive particles, to a clustering state and, finally, to a percolation network of interconnected clusters. The real part of permittivity, determined from refractometry and broadband dielectric spectroscopy experiments, displays an increase when the inserted particles are clustering up to the sub-percolative state. Beyond it, the material’s dielectric performance goes downward, while the conductivity rises up to semiconducting level. To maintain the dielectric breakdown at a level comparable at least to that of the polymer matrix, a new treatment was applied to the samples residing in shear casting of the filled polymer, film stretching and annealing. This work provides new insights on the design of eco-friendly dielectrics or semiconducting layers for future ‘green’ electronic devices.</p>