. - Investigation of magnetised plasmas by advanced diagnostics is a relevant topic in the frame of ion sources for high-performance particle accelerators and in thermonuclear fusion research for energetic purposes. In this paper, we propose two different diagnostic techniques to provide complementary information on plasma properties: high-resolution Optical Emission Spectroscopy (OES) and Microwave Reflectometry (MR). Several OES measurements have been carried out at INFN-LNS to determine cold electron plasma density and temperature in the framework of the PANDORA project. Experimental results will be here presented together with an ongoing R&D simulation work for the MR system to be employed in the Divertor Tokamak Test (DTT) facility in view of reconstructing the 1D electron density profile accurately. An overview of the perspectives and challenges of the two diagnostic systems will be given.