This paper provides an update inventory of the vascular flora and a framework of the plant communities of the Isole dei Ciclopi (Acicastello, Catania) taking into account their geological setting. A total of 111 phytosociological relevés were performed in the period 2015-2016. The plant communities has been analyzed using WPGMA and Euclidean distance classification. The study area preserves interesting plant-communities, mainly represented by shrubs vegetation (Oleo-Ceratonion siliquae and Pruno-Rubion ulmifolii), rocky coast communities (Crithmo-Staticion), cliff vegetation (Anthyllidion barbae-jovis), halo-nitrophilous vegetation (Pegano-Salsoletea), spring-flowering meadows (Frankenion pulverulentae) and nitrophilous communities (Allion triquetri and Echio-Galactition tomentosae). The vegetation analysis allow the identification of twelve vegetation types and also the reconstruction of three vegetation series. The collected data have been organized in a GIS and the following thematic maps have been produced: vegetation map, habitats map (according to the 92/43/EEC Directive). According to directive 92/43/EU, only three habitat types were delimited through the phytosociological assessment of the plant communities. The flora of the investigated area consists of 102 taxa. The majority of the taxa represented in the life form spectrum are therophytes and hemicryptophytes. From a chorological point of view, the Mediterranean element outweighs the rest, followed by the most diverse group of widespread taxa. Furthermore a detailed geological investigation was carried out and a geological sketch map was performed. The comparison between the vegetation and geological maps shows a good correlation, mostly regarding the distribution of the plant communities onto the different types of substrata.[es] La vegetación y su relación con el sustrato geológico: el caso de Isole dei Ciclopi (este de Sicilia, Italia)Resumen. Se presenta un inventario actualizado de la flora vascular y de las comunidades vegetales de la Isole dei Ciclopi (Acicastello, Catania) teniendo en cuenta su situación geológica. Se realizaron un total de 111 inventarios fitosociológicos en el período 2015-2016. Las comunidades de plantas se han analizado mediante clasificaciones (WPGMA, distancia euclídea). El área de estudio conserva interesantes comunidades vegetales, representadas principalmente por vegetación arbórea (Oleo-Ceratonion siliquae y Pruno-Rubion ulmifolii), comunidades costeras rocosas (Crithmo-Staticion), vegetación de acantilados (Anthyllidion barbae-jovis), vegetación halo-nitrófila-(Pegano-Salsoletea), comunidades terofíticas de carácter halófilo (Frankenion pulverulentae) y comunidades nitrófilas (Allion triquetri y Echio-Galactition tomentosae). El análisis de la vegetación ha permitido la identificación de doce tipos de comunidades y la reconstrucción de tres series de vegetación. Los datos recogidos se han organizado en un SIG y se han elaborado los siguientes mapas temáticos: mapa de vegetación, mapa de hábitats (Directiva 92/43/CEE)...