The Municipality of Nisyros includes Gyalí, as well as uninhabited Pacheiá, Pergoússa, Kandelioussa, Ágios Antónios and Strongýli.

The most recent plan was to gradually create and operate a geothermal plant with a capacity of 20 to 25 MW in cooperation with international specialized institutions.

[9] Given the estimated energy needs of Nisyros (1–2 MW), it was considered possible to supply electricity to the neighbouring islands of Kos, Tilos, Kalymnos, and Leros.

However, long-lasting protests by the local community of Nisyros have blocked any plans to exploit the geothermal field for years.

According to the 2011 census, the municipality's resident population is 1,008 (including 21 on Gyali), although in summer it is augmented by many tourists as well as expatriate Nisyrians who visit the island for their vacations.

According to Greek mythology, the island was formed when Poseidon cut off a part of Kos and threw it onto the giant Polybotes to stop him from escaping.

Between X-XI centuries, Genoese captains and adventurers who had a private fleet organized in clans united by family ties, exercised sovereignty and maritime control on behalf of the Byzantines, and these clans in exchange for the protection of the seas were given a concession to exploit raw materials, rights of trade and collection of customs duties.

The Knights Hospitaller in 1315 were allowed to settle on the island upon payment of rent to Genoese government ruled by the Vignolo family, and they built the crusader castle.

[citation needed] Many Orthodox Christian churches are found on the island, as well as four monasteries which are not inhabited by monks today, although various celebrations take place in them.

[citation needed] The largest monastery is the one of Panagia Spiliani (Blessed Virgin Mary of the cave) at Mandraki; it is built beside the medieval castle erected by the Knights Hospitaller.

[16][17] The diocese was nominally restored in 1927 as Titular See of the lowest (Episcopal) rank, initially named Nysirus (Curiate Italian Nisiro), and renamed Nisyrus in 1928.