AbstractIn the field of hybrid photovoltaic cell technology, the present work aims studying titanium dioxide layers with ordered nanostructure and poly-3-methylthiophene (P3MT) films in-situ electropolymerized onto them. Nanotube arrays were synthesized by anodization technique using a wide range of process conditions, and the dimensions and morphology of the obtained nanotubes were thoroughly analyzed. This study allowed tailoring the nanotube dimensions as requested by the final application. In this case, arrays with low thickness and large pore diameter, obtained in the acidic water based electrolyte, were selected to carry out further electropolymerization onto them. The nanotube pore diameter was identified as the dominant parameter influencing the P3MT layer thickness. The P3MT layers with the lowest thickness were obtained onto the less porous morphologies with low nanopore diameter values.