The public sector in Norway, particularly municipalities, is currently transforming through the adoption of cloud solutions. This multiple case study investigates cloud adoption and is security challenges that come along with it. The objective is to identify the security challenges that cloud solutions present and techniques or strategies that can be used to mitigate these security challenges. The Systematic Literature Review (SLR) provided valuable insights into the prevalent challenges and associated mitigation techniques in cloud adoption. The thesis also uses a qualitative approach using Semi-Structured Interviews (SSI) to gather insight into informants’ experiences regarding cloud adoption and its security challenges. The study’s empirical data is based on interviews with six different Norwegian municipalities, providing a unique and broad perspective. The analysis of the empirical findings, combined with the literature, reveals several security challenges and mitigation techniques in adopting cloud solutions. The security challenges encompass organizational, environmental, legal, and technical aspects of cloud adoption in the municipality. Based on the findings, it is recommended that Norwegian municipalities act on these issues to ensure a more secure transition to cloud solutions
