We present our recent efforts in the build-up of a room temperature electron spin noise scanning tunnelling microscope (ESN-STM) designed for ultra-thin molecular films investigation. We describe here the first results obtained with this system on a commercial paramagnetic molecule deposited on Au(1 1 1) surfaces, namely 1,1-diphenyl-2-picrylhydrazyl (DPPH). Further we briefly present our ongoing work on the preparation and characterization of a new class of samples for this instrumentation. These are based on the self-assembling on surfaces of functionalized organic radicals. We suggest here a complete procedure to assess a good candidate molecule for ESN-STM experiments through X-band CW-ESR, standard STM investigations and ToF-SIMS analysis.