Astet is located some 30 km west by north-west ofAubenas and 15 km east by south-east ofLangogne. Access to the commune is byRoute nationale N102 fromLanarce in the north-west passing through the north of the commune and continuing over the Col de la Chavade in the centre of the commune then south-east toMayres. The N102 is a heavily used road between theRhône Valley and theMassif Central. There is also the D239 coming fromSaint-Cirgues-en-Montagne in the north-east passing through the centre of the commune, crossing the N102 at the Col de la Chavade and continuing south to join the D19. The village is located in the east of the commune and is reached by a short but tortuous road from the N102. Apart from the village there is also the hamlet of Sedassier to the south-east. The commune covers 3,445 hectares with the highest point atLes Valadous at 1,548m.[3]
TheArdèche river has its source in the centre of the commune and it flows south-west gathering many tributaries in the commune: the Ruisseau des Chaplades, the Ruisseau de Paillayre, the Ruisseau de Pierne, the Ruisseau de la Bessede, the Ruisseau de Fiagouse, the Ruisseau des Gardettes, the Ruisseau de Pierne, and the Ruisseau de la Bessede. It begins its journey to join theRhône atPont-Saint-Esprit in Astet. The Espezonnette rises in the south of the commune with many tributaries: the Ruisseau de la Ferme, the Ruisseau du Gouffre, the Ruisseau de Montgros, and the Ruisseau de l'Ane. It flows north forming a small part of the northern border before continuing to join theAllier just south of the Langogne-Lesperon Aerodrome.[3]
First established as a parish in 1770, Astet became a commune in 1907 by separating from the large commune ofMayres. Astet had over 500 inhabitants in 1911 but this has decreased to 41 in 2010. TheFirst World War resulted in a reduction in population then thedesertification of the land in the 1950s.