The CMS-CASTOR calorimeter is designed to study the very forward, baryon-rich region in heavy ion collisions. Together with ZDC, it will make possible the covering of almost the whole angular region for CMS. CASTOR consists of quartz plates in a heavy metal matrix. Cherenkov light produced in the quartz plates will be detected by Hamamatsu R5380 Photomultipher Tubes (PMTs). All the PMTs which will be used in the calorimeter have to be verified for gain and timing characterisation to have the performance required by CMS-CASTOR Group before their installation into the calorimeter. We established a testing station at Cukurova University for this purpose. In the present paper we are going to give the anode dark current and gain measurements of these PMTs.