At ORCI, the Co-60 source with two gamma rays having energies of 1.17 MeV and 1.33 MeV which are is used for treatment of cancer of gynaecological malignancies in the HDR brachytherapy unit. The Room Scatter Factor, Kscatter suitable to a treatment room must be known before determination of reference air Kerma rate. This is because K the geometry set up of the source to chamber and immediate environment (IAEA, TECDOC1274, Faiz 2010). The 60Co source with an 2.0 Ci was installed in the treatment unit at the ORCI. The room scatter factor need to be known in order to determine reference Air Kerma Strength, . The objective of this study was to determine room scatter factor suitable for Ocean Road Cancer Institute (ORCI) High Dose Rate (HDR) Brachytherapy room and is reported in this paper.