Advances in transport refrigeration and air-conditioning systems used in ships have evolved over many years. Today’s systems must incorporate the latest available technologies, taking into consideration current and future regulatory requirements for refrigerants with low Global Warming Potential, energy efficiency, indoor air quality, food quality standards and customer expectations around total operating costs. A summary of transport refrigeration system technologies generally, along with marine air-conditioning systems, is presented and includes associated technical challenges, trade-offs and potential design impacts.