In his activity as researcher and coordinator of research activities prof. Rapuano deals with digital processing of measurement signals, characterization of analog-to-digital and digital-to-analog converters, distributed measurement systems, design of measurement methods and systems for telecommunications, distance learning in the field of electrical and electronic measurements, biomedical measurements, authoring about 270 documents including journal papers, conference papers, book chapters and IEEE standards. He participated and coordinated research projects funded by national and international entities.