In this study, three Ranque-Hilsch vortex tubes were used, which have 9 mm inside diameter and length/diameter ratio was 15. Their performances were examined as one of the classical RHVT and other was hot cascade type RHVT. Performance analysis was according to temperature difference between the hot outlet and the inlet (Delta T-hot.). The Delta T-hot values of hot cascade type Ranque-Hilsch vortex tubes were greater than the Delta T-hot values of classical RHVT, which were determined experimentally. The total inlet exergy, total outlet exergy, total lost exergy and exergy efficiency of hot stream were investigated by using experimental data. In both the classical RI-PIT and hot cascade type RHVT, it was found that as fraction of cold flow increases the total lost exergy decreases. It was also found that, the hot cascade type RHVT more exergy efficiency of hot outlet than the classical RHVT. Excess Delta T-hot value of hot cascade type Ranque-Hilsch vortex tube causes the excess exergy efficiency of hot outlet. (C) 2011 Elsevier Ltd and IIR. All rights reserved.