This paper describes a data integration tool used to identify potentially undiscovered geothermal resources in the island of Sicily. The factors facilitating the recovery of exploitable geothermal energy were defined, and their spatial correlation established by Geographic Information System (GIS) models.By prioritizing favourable conditions using an Index Overly method, "favourability" maps of Sicily were obtained. The maps considered both geological and economic aspects, and energy recovery was considered for current technologies. Our approach and maps are useful for developing and planning local or national energy policies including geothermal energy.