PCO AG 1 article published in JoVE Chemistry Luminescence Lifetime Imaging of O2 with a Frequency-Domain-Based Camera System Maria Moßhammer*1, Vincent V. Scholz*2, Gerhard Holst3, Michael Kühl1,4, Klaus Koren5 1Marine Biological Section, Department of Biology, University of Copenhagen, 2Center for Electromicrobiology, Aarhus University, 3PCO AG, 4Climate Change Cluster, University of Technology Sydney, 5Aarhus University Centre for Water Technology, Section for Microbiology, Department of Bioscience, Aarhus University We describe the use of a novel, frequency-domain luminescence lifetime camera for mapping 2D O2 distributions with optical sensor foils. The camera system and image analysis procedures are described along with the preparation, calibration and application of sensor foils for visualizing the O2 microenvironment in the rhizosphere of aquatic plants.