Peritoneal surface malignancies are a group of cancers associated with poor prognosis. Advances in surgical oncology, primarily in the form of surgical cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC), have shown potential to provide a survival benefit to these patients. In this context, therapeutic hyperthermia refers to the deliberate administration of heat via the chemotherapy solution to increase the effectiveness of such therapy. Locoregional hyperthermia can exert its effects via multiple mechanisms, including direct cytotoxic effects and improving the pharmacologic profile of the chemotherapeutic agent. While scientific advances in thermal dosimetry have established important principles, there is a significant gap between those understood in basic science or computational modeling and those applied in clinical practice. The existing knowledge gaps can largely explain the conflicting experimental clinical evidence supporting the use of HIPEC, with some landmark studies supporting a survival advantage and others suggesting higher morbidity in those receiving HIPEC. To establish a clinical benefit of hyperthermia in HIPEC, it is necessary to standardize thermal dosimetry beyond the current practice which measures the intrabdominal fluid temperature during perfusion, which appears insufficient to predict treatment effectiveness. In this chapter, we aim to contextualize the reader about the use of hyperthermia in peritoneal surface malignancies. Below, we discuss its mechanisms of action, the dosing principles, and the recent advances in computational modeling of intrabdominal hyperthermia. Finally, we will summarize the HIPEC techniques and perfusion protocols, and the disease-specific evidence guiding clinical practice.