Abstract The development of sugarcane varieties has allowed Brazilian ethanol plants to operate longer during the harvest, however, in the off-season they remain idle due to the absence of biomass. To increase energy safety and guarantee supply in critical periods, it has been proposed to adapt ethanol plants to the flex-biomass model, allowing the production of biofuel from corn as well. Considering the costs of building or adapting a plant, strategically defining the location is essential for optimizing ethanol production. The aim of this study is to verify whether the combination of location criteria can identify the most suitable regions for the construction of new plants and map them. The method consists of the Analytical Hierarchical Process (AHP) with GIS techniques. We found two large continuous regions suitable for the construction of new flex ethanol plants, corresponding together to 11% of the study area. However, in these two suitable regions, only 0.33% of the territory has more than 90% suitability. Therefore, we confirmed the existence of more suitable regions and concluded that the mapping of these areas enhances the resources application, avoiding installation in inappropriate areas.