The present work deals with the problem of monitoring and diagnosis, through non-intrusive methodologies, of stationary internal combustion engine, with particular attention to the cogenerative 1 MW unit installed at the Engineering Faculty of the University of Perugia. Specifically, acoustic and vibrational measurements have been performed to correlate the engine functional status (and therefore the vibration of mechanical surfaces) with the acoustic emissions features through the characteristic radiation factor. The ISO/TS 7849 normative for the correlation of vibration and acoustic measurement has been employed. (C) 2012 Elsevier Ltd. All rights reserved.