A full study of the BaTiO3-CuO thin-film technology properties as carbon dioxide sensing material is presented. The coatings are deposited by RF-Sputtering and the CO2 concentration is monitored by impedance measurements. Theoretical foundations are correlated to the experimental results and the principal fabrication and operation parameters are clarified: working temperature and frequency, thickness influence and the introduction of silver as an additive. The BaTiO3-CuO layer shows higher sensitivity than the actual low-cost commercial CO2 sensors in the range of the principal applications. (C) 2009 Elsevier B.V. All rights reserved.