CsI photocathodes were studied in order to evaluate their potential use as large photoconverters in RICH detectors for the PID system at ALICE (LHC in heavy ion collider mode). It has been demonstrated that a quantum efficiency comparable to the reference value obtained on small samples can be obtained on CsI layers evaporated on large pad electrodes operated in a MWPC at atmospheric pressure. We present a survey of the results obtained in the laboratory on small samples irradiated with UV-monochromatic beams and with RICH detectors of proximity-focusing geometry at a 3 GeV/c pion beam.