In this study, the effects of six different working fluids, hexane, petroleum ether, chloroform, acetone, methanol and ethanol on the energy and exergy performance are investigated in evacuated tube solar collectors with thermosyphon heat pipe under three different air velocities as 2, 3 and 4 ms(-1). The six evacuated tube solar collectors with thermosyphon heat pipe with the same dimensions and properties are designated for the air heating and tested under the outdoor climatic conditions of Usak, Turkey. The lowest energy and exergy efficiencies occur in the THPETC-Hexane under 2, 3 and 4 ms(-1), the highest energy efficiency occurs in the THPETC-Acetone for air velocity of 2 and 3 ms(-1) and in the THPETC-Chloroform for air velocity of 4 ms(-1). The highest exergy efficiency occurs in the THPETC-Acetone for air velocity of 2 ms(-1) and in the THPETC-Chloroform for air velocity of 3 and 4 ms(-1). (C) 2016 Elsevier Ltd. All rights reserved.