[en] I present an overview of the BeppoSAX program in the field of optically thin plasmas, which comprises stellar coronae, supernova remnants and clusters of galaxies. Albeit only ∼ 70% of the observations approved in AO1 have been carried out, and only part of the acquired data have as yet been analysed, there are already significant, and in some case unique results coming out from the ongoing program. The analysis carried out so far, although preliminary, is very important for assessing the capabilities of the BeppoSAX mission and for optimizing future observations