The Internet of Things (IoT) is one of the most recent information communication technology (ICT) phenomena to have had a global impact upon wireless telecommunications. Due to the benefits of the IoT in terms of developing communication and connectivity between devices, businesses are thus able to enhance profitability, reduce operational costs, become customer-centric and eventually gain sustainable competitive advantage. Identifying and understanding the factors that affect the IoT adoption is critical in order that either the success or failure of an organisation can be determined. The existing literature, however, does point to a knowledge gap regarding IoT adoption in the manufacturing SME sector, in particular within developing countries. This study examines factors that affect IoT adoption within manufacturing SMEs in Thailand and provides further insights into those factors and their interaction. The theories of technology adoption, such as diffusion of innovation and technology organisation environmental framework, form the theoretical underpinnings of this thesis. Drivers and barriers, or factors, which promote or hinder IoT adoption respectively are of particular relevance. The research adopts a qualitative approach by conducting multiple case studies within 10 manufacturing SMEs in Thailand. Both within-case and cross-case analysis are used to conduct these case studies and this leads to the identification of common themes and categories impacting IoT adoption. The study finds that relative advantage, compatibility, business partner influence, trialability, top management support, organisational structure, technology support from vendors, observability, cost, and security and privacy are perceived to influence the decision of whether adoption of the IoT by Thai manufacturing SMEs is undertaken. Within these 10 factors, relative advantage and business partner influence are found to be the most significant drivers, whereas compatibility is found to be the most significant barrier. This study makes both practical and theoretical contributions to the growing body of knowledge regarding IoT adoption. The major theoretical contribution of this thesis is that it provides increased insight into the usage, applications and factors that affect the decision to adopt the IoT within the context of manufacturing SMEs in Thailand. The study presents a conceptual framework that highlights the factors affecting adoption of the IoT in manufacturing SMEs. The major practical contribution of this study is the information provided for policymakers, managers in organisations, technology consultants, and vendors in order that they may effectively implement and accelerate IoT development and utilisation among Thai manufacturing SMEs. Managers of SMEs could use this study as a reference upon which to base effective decision-making with regard to whether to adopt the IoT or not, and also for developing policies that could guide further adoption. Furthermore, IT vendors/consultants could use this study to gain productive insight into the specific problems and requirements faced by manufacturing SMEs when they are thinking about adopting IoT systems, thus enabling IT consultants to design suitable strategies for the widespread adoption of the IoT. This study is the first to examine IoT adoption in the context of manufacturing SMEs in Thailand and its findings will be relevant in other, similar developing world economies.