This study reports the thermal conductance and thermal conductivity of a suspended metallic single-wall carbon nanotube (SWNT) over the temperature range of 300–800 K. The thermal conductance is approximately 2.4 nW/K, and the thermal conductivity is nearly 3500 Wm⁻¹K⁻¹ at room temperature for a SWNT of length 2.6 μm and diameter 1.7 nm. A subtle decrease in thermal conductivity steeper than 1/T is observed at the upper end of the temperature range, attributed to second-order three-phonon scattering between two acoustic modes and one optical mode. The study presents an analytical model for the SWNT thermal conductivity, including length and temperature dependence. Single-wall carbon nanotubes (SWNTs) have attracted significant scientific and engineering interest due to their exceptional electrical and thermal properties. They are being explored for applications in integrated circuits and thermal management. Understanding their thermal properties is crucial for their practical use. While theoretical studies on SWNT thermal conductivity exist, few experimental estimates are available, and no studies have been conducted above room temperature. This study fills that gap by measuring the thermal conductance of an individually suspended SWNT in the 300–800 K range. The study uses Joule self-heating to measure the thermal properties of the SWNT. The SWNT was suspended across Pt contacts and pre-defined trenches. Electrical characterization was performed in vacuum at ambient temperatures between 250 and 400 K. The measured I-V characteristics of the SWNT were used to extract its thermal properties. The thermal conductance was determined by analyzing the high-bias electrical characteristics, which are limited by Joule self-heating and strong electron scattering with high energy optical phonons. The study models the resistance of the SWNT using the Landauer-Büttiker approach. The thermal conductivity was extracted by solving the heat conduction equation and adjusting the thermal conductivity input until agreement with the measured I-V data was achieved. The thermal conductivity was found to decrease more steeply than the expected 1/T at the upper end of the temperature range, attributed to second-order three-phonon scattering processes. The study also presents an analytical model for the length and temperature dependence of SWNT thermal conductivity. The model was validated against experimental data and shows good agreement with more sophisticated simulations. The results provide the first high-temperature study of SWNT thermal properties and complement existing data sets. The study highlights the importance of understanding thermal contact resistance in determining the intrinsic thermal properties of nanostructures.This study reports the thermal conductance and thermal conductivity of a suspended metallic single-wall carbon nanotube (SWNT) over the temperature range of 300–800 K. The thermal conductance is approximately 2.4 nW/K, and the thermal conductivity is nearly 3500 Wm⁻¹K⁻¹ at room temperature for a SWNT of length 2.6 μm and diameter 1.7 nm. A subtle decrease in thermal conductivity steeper than 1/T is observed at the upper end of the temperature range, attributed to second-order three-phonon scattering between two acoustic modes and one optical mode. The study presents an analytical model for the SWNT thermal conductivity, including length and temperature dependence. Single-wall carbon nanotubes (SWNTs) have attracted significant scientific and engineering interest due to their exceptional electrical and thermal properties. They are being explored for applications in integrated circuits and thermal management. Understanding their thermal properties is crucial for their practical use. While theoretical studies on SWNT thermal conductivity exist, few experimental estimates are available, and no studies have been conducted above room temperature. This study fills that gap by measuring the thermal conductance of an individually suspended SWNT in the 300–800 K range. The study uses Joule self-heating to measure the thermal properties of the SWNT. The SWNT was suspended across Pt contacts and pre-defined trenches. Electrical characterization was performed in vacuum at ambient temperatures between 250 and 400 K. The measured I-V characteristics of the SWNT were used to extract its thermal properties. The thermal conductance was determined by analyzing the high-bias electrical characteristics, which are limited by Joule self-heating and strong electron scattering with high energy optical phonons. The study models the resistance of the SWNT using the Landauer-Büttiker approach. The thermal conductivity was extracted by solving the heat conduction equation and adjusting the thermal conductivity input until agreement with the measured I-V data was achieved. The thermal conductivity was found to decrease more steeply than the expected 1/T at the upper end of the temperature range, attributed to second-order three-phonon scattering processes. The study also presents an analytical model for the length and temperature dependence of SWNT thermal conductivity. The model was validated against experimental data and shows good agreement with more sophisticated simulations. The results provide the first high-temperature study of SWNT thermal properties and complement existing data sets. The study highlights the importance of understanding thermal contact resistance in determining the intrinsic thermal properties of nanostructures.