The cancer therapy, magnetic hyperthermia, was proposed 60 years ago. Despite decades of efforts, this technique is still in its research stage. An ex-vivo experiment presented in Chapter 1 shows that one of the main barriers lies in its temperature measurement. The current gold standard is to insert a thermal probe into the target tumour. The measurement of which is invasive and point measurement only. Because of the inhomogeneous particle distribution, the accuracy of point measurement relies on accurate placement of the thermal probe, which is difficult to achieve. Thus, this study investigates two alternatives of point measurement. The first alternative is an existing technique, i.e., infra-red thermography and the second is a thermometry proposed in this study. The latter is termed as magnetic particle thermometry (MPT). Before discussing these two methods of temperature sensing, Chapter 2 reviews concepts such as the biological effects of heat, the mechanism of magnetic heating, and other remote sensing methods. Subsequent to this, Chapter 3 and Chapter 4 respectively present in-vitro and in-vivo experiments to evaluate the implementation of infra-red thermography in magnetic hyperthermia. In which, the effects of particle distribution and the thermal doses on hyperthermia are discussed. The result suggests that the infra-red thermography is applicable to studies involving subcutaneous tumours. When treating a deep-seated tumour, another sensing method is still desired. Chapter 5 then describes the principles of proposed MPT. The MPT assesses the average temperature of the target tumour by detecting the average temperature of the deposited magnetic nanoparticles. The MPT is possible because the temperature of magnetic nanoparticles would interfere the resonant frequency of the field applicator. By tracking the shift in resonant frequency of the field applicator, the average temperature of particles is estimated. The theory of which is carefully validated through a series of experiments presented in Chapter 6.