Infra-red radiation from volcanoes can be studied in the 3–5 and 8–14 μm wavebands by ground-based, aerial. and satellite surveys. The occurrence of a volcanic eruption is preceded by the introduction of hot magma beneath the volcano which may give rise to a detectable surface thermal anomaly, especially in the case of slow-moving andesitic magmas. Ground-based surveys employing simple infra-red telescopes are capable of rapidly producing thermal maps of volcanoes, but consistent monitoring is required to distinguish between apparent and real thermal anomalies. Aerial surveys employing scanning instruments to create thermal images provide better data, but present the same problems of interpretation. Satellite infra-red systems do not have resolutions below 120 m, but offer great potential for the future. Aerial surveys are too expensive to be used for routine volcano monitoring. Ground-based surveys are advocated until satellite infra-red resolution is improved.