The efficiency and effectiveness of solar energy capture and storage are to a large extent functions of the heat transfer and storage capacity of the medium used. This paper investigates the potential of using carbon nanotube (CNT)-glycol nanosuspension as such a medium, prepared by freeze drying-ultrasonic dispersing after oxidation treatment with HNO 3 . The influences of the mass fraction of CNTs glycol nanofluids and temperatures on photo-thermal properties, thermal conductivities and rheological behavior were investigated. The results show that CNTs with oxidation treatment exhibited good dis- persing performance. Strong optical absorption of the CNTs glycol nanofluids was detected in the range of 200-2500 nm. At room temperature, 18% enhancement was found in the photo-thermal conversion efficiency of the 0.5% mass fraction CNTs glycol nanofluids in comparison to the basic fluids, without significant increase in viscosity. At 55 C, CNTs glycol nanofluids with 4.0% mass fraction exhibited much lower viscosity and 25.4% higher thermal conductivity in comparison to that of pure glycol at room temperature. The efficiency and effectiveness of solar energy capture and storage are to a large extent functions of the heat transfer and storage capacity of the medium used. This paper investigates the potential of using carbon nanotube (CNT) -glycol nanosuspension as such a medium, prepared by The influences of the mass fraction of CNTs glycol nanofluids and temperatures on photo-thermal properties, thermal conductivities and rheological behavior were investigated. The results show that CNTs with oxidation treatment showed good dis- persing performance. Strong optical absorption of the CNTs glycol nanofluids was detected in the range of 200-2500 nm. At room temperature, 18% enhancement was found in the photo-thermal conversion efficiency of the 0.5% mass fraction of CNTs glycol nanofluids in comparison to the basic fluids, without significant increase in viscosity. At 55 C, CNTs glycol nanofluids with 4.0% mass fraction ex hibited much lower viscosity and 25.4% higher thermal conductivity in comparison to that of pure glycol at room temperature.