Process analytical technology (PAT) is a framework that allows real-time process monitoring. To date there has been limited adoption PAT tools in the dairy industry. Some of the major benefits of use of PAT tools include consistent and improved final quality and throughput of dairy products using continuous process monitoring. The overall goal of this thesis was to develop and validate novel PAT tools for monitoring selected dairy processes. PAT tools were investigated for process optimization and ensuring product quality, reducing energy usage, operation cost and waste (e.g. product rework) in dairy processing. Four research studies were carried out at laboratory and/ or pilot scale using acoustic sensors, Raman spectroscopy, electrical resistance tomography (ERT) and focused beam reflectance measurement (FBRM) PAT tools. Overall, this thesis validated four novel PAT tools, and demonstrated their potential to provide real-time process information and control selected dairy processes (acid-induced milk coagulation, UF process, milk fat crystallization and melting, and dairy powder rehydration). Industry adoption of the PAT tools reported in this thesis has strong potential to enhance the efficiency of dairy processing. It is recommended that the PAT tools used in this thesis should be further validated to demonstrate their robustness before commercial adoption in the dairy industry. In particular, the PAT tools should be assessed under a wider range of product and process parameters, and over longer production runs.