Activities on superconducting accelerating cavities at LNF

In the framework of the Linear Superconducting Accelerator (LISA) project, a facility was setup for testing 500-MHz single-cell cavities in a vertical cryostat. To investigate the effect of different chemical treatments, bulk Nb single cells welded from the inside were constructed in cooperation with national manufacturers. Preliminary results of the RF measurements in a cryogenic environment are reported and discussed.