Objective: The objective of this study was to analyse the spatial distribution and amount of potential biomass feedstock for biomethane production and optimal locations, sizes and number of biogas plants in southern Finland in the area of three regional waste management companies. Methods: A Geographical Information System (GIS) based methodology, which also included biomass transport optimisation considering the existing road network and spatially varied biomass sources, was used. Kernel Density (KD) maps were calculated to pinpoint areas with high biomass concentration. Results: The results show that the total amount of biomass corresponds to 2.8 TWh of energy of which agro materials account for more than 90%. It was found that a total of 49 biogas plants could be built in three case regions with feedstock available within maximum transportation radius of 10 or 40 km. With maximum of 10 km biomass transportation distance, the production capacity of the planned plants ranges from 2.1 to 8.4 MW. If transportation distance was increased to 40 km, the plant capacities could also increase from 2.3 to 16.8 MW. Conclusions: As demonstrated in this study, the studied GIS methodology can be used for identification of the most suitable locations for biogas plants by providing the tools for e.g. transportation routes and distances. Practice implications: The methodology can further be used in environmental impact assessment as well as in cost analysis. (C) 2013 Elsevier Ltd. All rights reserved.