The NAPP Project, led by Luca Artiglia since September 2015, was started in 2013 after the purchase and commissioning of a commercial Scienta R400 Hipp-2 ambient pressure photoelectron analyzer. The main goal is to characterize the surface of real catalysts either in-situ or under operando conditions by means of X-ray photoelectron spectroscopy carried out in the millibar range. We aim at understanding the physico-chemical properties of catalysts under reaction conditions, and to identify what are the active species involved in the mechanism