Recebido em 5/1/04; aceito em 24/8/04; publicado na web em 17/2/05 PREPARATION OF OPTICALLY TRANSPARENT ELECTRODES. A simple experiment for the preparation of transparent conducting glass electrodes by deposition of pure and fluorine doped SnO 2 films is described. This procedure was tested in the undergraduate inorganic course at IQ-UNICAMP. The success in achieving a conducting layer was easily checked using the standard probes of a volt-ohm meter. The optical transmittance and thickness were studied by UV-vis spectrophotometry. To discuss the experimental results we place significant emphasis on molecular orbital and energy band model theories. The undergraduate students can also discuss the concepts related to the electronic properties of solids and to interesting new materials, such as transparent conducting films, which are the subject of significant current research and technological applications.