This International Standard specifies the multiple measurement methods, instruments, equipment, and samples used to calculate the thermo-optical properties of thermal control materials. This International Standard compares their features, indicates their limitations and biases, and guides the applications. These measurements will be performed at ground test facilities with the purpose of obtaining material properties. The measured properties will be used for material selection, thermal design of spacecraft, process control, quality control, etc. Also, on-orbit temperature data in the beginning of life can be assessed using the data obtained by ground measurement. Requirements for calibration and reference materials to ensure data quality are also defined. The following test methods are detailed in the Annexes of this International Standard including the configuration of samples and calculations. a) Solar absorptance using a spectrophotometer: (αs) — Annex A b) Solar absorptance using the comparative test method: (αp) — Annex B c) Hemispherical infrared emittance using the thermal test method: (εh-t) — Annex C d) Normal infrared emittance using an IR spectrometer: (εn-s) — Annex D e) Normal infrared emittance using ellipsoid collector optics (εn-e) — Annex E f) Normal infrared emittance using two rotating cavities: (εn-c) — Annex F