This project concerns the understanding of the thermodynamic properties of higher spin black
holes in AdS3. Through the conjectured Minimal Model/Higher Spin duality, the partition
functions of such black holes should be equal to partition functions in the presence of
chemical potentials in an appropriate dual 2d CFT. In the well-understood spin-2 case, the
modular properties of partition functions play a major role in understanding their behaviour
at high and low temperatures, and the goal of this dissertation is to obtain an analogous
understanding of modular properties in the higher-spin case.