The Atmospheric Chemistry Laboratory (ACL) of the National Observatory of Athens (NOA) was founded in 1996 by the Institute for Environmental Research and Sustainable Development (IERSD), one of NOA’s three institutes. ACL/NOA is located at the IERSD’s premises in P. Penteli. In 2005, the Laboratory upgraded its existing infrastructure, in order to be able to provide chemical analysis and air pollutant measurement services, with emphasis on hazardous for public health chemical compounds and species that are harmful to the environment. The immediate objective of ACL/NOA is the provision of high quality services for measuring atmospheric pollutants, in order to meet the demands of Greek society, state and private bodies, for sustainable economic and technological development, coupled with environmental and public health protection. ACL/NOA participates in national and international research projects, conducting both basic and applied research, among others within the fields of Atmospheric Chemistry and Physics and Air Quality. The laboratory equipment includes a variety of analytical instruments for chromatographic and spectroscopic applications, as well as auxiliary equipment and sampling devices. Gravimetric filter measurements for particulate matter (PM) concentrations are conducted in a controlled weighing room. The oxidative potential (OP) of water soluble ambient aerosols is determined by a state of the art semi-automatic analyzer developed in collaboration with the Georgia Institute of Technology, using the Dithiothreitol (DTT) assay. Modification of the system can also provide the absorption of brown carbon (BrC) of water soluble aerosol.