As the United Nations (UN) is a complex organization carrying out divers tasks in the world, most functions for an enterprise GIS are required. In order to support the requirements from the UN, the UN Open GIS Initiative was founded in 2016 with goals to provide GIS solutions for the UN based on open source software. The working group 3 of the initiative, named Spiral 3, aims to develop and deliver geo-analytic functions to the UN. In particular, a number of geo-analytic functions are developed by Spiral 3 to support field operations such as UN peace keeping operation. In this paper, we present a development use-case of geo-analytic functions for the UN, which is composed of four steps; analysis of requirements and functional specification, definition of development environment and system architecture, system development and test, and documentation of user manual and education materials. First, a comprehensive study on UN operations has been carried out, which covers the following tasks; situational awareness, security operations, military operations, protection of civilians, human rights violation investigation, epidemiological analysis, mission’s support and logistics operations, electoral support, disarmament, demobilizations and reintegration program, and humanitarian response operations. From this study, we derived 26 primitive geo-analytic functions. The users of geo-analytic functions for these tasks include mostly officers at field offices and geo-analysis experts at mission headquarters. Second, the system development environment was determined as Java using GeoTools for the compatibility and portability. The geo-analytic functions were developed as a plug-in of uDig, which is a Java-based open source desktop GIS. It means that the preparation and pre-processing of data for geo-analysis and the visualization of the analysis are supported by uDig. Third, an experiment of the developed system was performed with a scenario of Ebola virus spread. It shows that the system properly supports the field operations of Ebola virus spread. The experiment also shows the strength and weakness of the developed geo-analysis functions in comparison with commercial GIS. As the fourth step of the development, a user-manual is published via web and an education material was also developed under the OSGeo-UN Committee Educational Challenge Program. Through the use-case study presented in the paper, we would like to share the experiences and lessons about the development of geo-analytic functions, which would be used as a reference for other geo-analytic function development.