Porous silicon (PS) has been an attractive material for bio-chemical sensors. Pore volume and surface area of the porous silicon are key parameters for the sensor applications. Its large surface area for the applications and compatibility with silicon-based technologies has been the driving force for this technology development. The carbon dioxide (CO2) gas is one of the most important greenhouse gases that cause global warming and air pollution. For this reason, detection of CO2 gas in living environment is essential. In this study, luminescence and electrical properties of the PS under different carbon dioxide levels and detection mechanisms were investigated. PS are fabricated by anodic etching in hydrofluoric acid based solution in a double anodization cell. The surface bond configurations and structural properties of PS were monitored by Fourier Transmission Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), respectively. The experimental results suggested that the PS surface very sensitive to CO2 gas and can be used for CO2 sensing. (C) 2018 Elsevier GmbH. All rights reserved.