The dataset contains tabular information about 979 organizations in 15 countries of Southeastern Europe that have been identified as Open Science stakeholders within the framework of the project NI4OS-Europe, funded by the European Commission under the INFRAEOSC-5b call. It was collected between early July and late-October 2019 based on the information provided by project partners from Albania, Armenia, Bosnia and Herzegovina, Bulgaria, Croatia, Cyprus, Georgia, Greece, Hungary, Moldova, Montenegro, North Macedonia, Romania, Serbia and Slovenia. Detailed information about the context and rationale behind collecting the dataset can be found in Deliverable D2.1 Stakeholder map, inventory, policy matrix, prepared within the scope of the NI4OS-Europe project. The stakeholders are classified into five groups based on their role in the research ecosystem: FUND (research funders and policymakers), CREATE (universities, research institutes, etc.), SUPPORT (libraries, repositories, research infrastructures, etc.), CONSUME (organizations using research results in their work, e.g. SMEs) and FACILITATE (individuals and organizations involved in promoting the principles off open science). The dataset contains the following information for each entry: country, stakeholder category/role, official/legal name of the organization, city, Zipcode, addresses (street name and number), URL of the institutional website, geographic coordinates (latitude and longitude). ****Dataset contents**** NI4OS_Stakeholder_Map_20200318.csv, data file, comma-separated values README.txt, metadata, text format ****Column headers and field types*** Country (text) StakeHoldersRole (text, ItemList{fund,create,facilitate,consume,support}) InstitutionName (text) City (text) Zipcode (text) Address (text) URL (text-web address) Latitude (number.decimal(2,7)) Longitude (number.decimal(2,7)) Data from this dataset have been quality-checked by the NI4OS-Europe project team. We recommend these data for further use. The dataset was used to generate an interactive map: https://ni4os.eu/os-stakeholders-map/