Geographic Information System (GIS) has many applications in a variety of fields. This thesis investigates the adoption of GIS in the public sector of a developing country, which has an emerging economy, namely Saudi Arabia. There is paucity in this body of literature on the area of GIS adoption, especially in regards to the Saudi Arabian public sector; therefore, why such an investigation is important. A model was proposed for GIS adoption and its outcomes, namely GIS Adoption Model (GISAM),where hypotheses were drawn from it. Testing the hypotheses of this model was performed on a government organisation that is the Ministry of Water and Electricity (MOWE),water sector in Saudi Arabia. The 297 survey responses were collected through a web-based structured survey questionnaire. Several statistical techniques were applied to the data collected such as correlations and regression analysis. This thesis develops an innovative model for GIS adoption in the public sector and its outcomes in the Saudi Arabian context. GISAM has four groups of factors that their impact on individuals‟ perception toward GIS will be tested. These four groups are organisational factors, technical factors, individual factors and socio-political factors. There are also the moderating demographic factors that their moderating effect on the relationship between determinants and perception toward GIS is tested as well. This model also considers the actual usage of GIS and how it is affected by individuals‟ perception of GIS; in addition, the thesis finally considers the expected outcomes from this adoption. The expected outcomes are divided into two groups: economic and social benefits. This model will add to the body of knowledge in the technology acceptance and adoption literature, especially the GIS literature. This thesis considered and tested the following determinants, which include GIS training, incentives, managerial support, IT expertise, exposure to GIS technology, perceived usefulness, personal innovativeness, image, geography knowledge, cartography knowledge, peers, social network and cultural values. Results showed that the only significant drivers were GIS training, managerial support, IT expertise, personal innovativeness, geography knowledge, cartography knowledge, peers, social network and cultural values. These determinants/drivers had impacts on perception toward GIS. Perception toward GIS turned out to have impacts on the adoption of GIS. The following outcomes/benefits were also tested, these include efficient decision-making, cost saving, better strategic planning, job satisfaction, efficiency of service, improved customers‟ satisfaction, quality of service, enhanced risk management and improved customer relationship. As a result, it was found that the significant outcomes of GIS adoption were efficiency of service, speed of service, quality of service, enhanced risk management and improved customer relationship.