The first stars and quasars to form in our universe drove a universal phase transition
known as epoch of reionisation, where the diffuse hydrogen gas between galaxies was
ionised. The epoch of reionisation is the last period in the history of our universe to
be studied in detail, and requires detailed theoretical models in order to interpret our
observations. Cosmological simulations provide a way to create detailed approximations
of physical processes on large scales that are impossible to solve analytically. This allows us to draw connections between the physical parameters we wish to know, and the
observable data we measure. In this thesis, we use different types of cosmological simulations to study the epoch of reionisation. We use the semi-analytic galaxy evolution
model Meraxes to place constraints on the epoch using measurements of the intergalactic medium temperature. We use the hydrodynamic simulation Bluetides to make
predictions for a future observational strategy where radio images of bright galaxies are
stacked together to measure their average signal. Finally, we make enhancements to a
hydrodynamic simulation code, MP-Gadget intended for use in the Asterix simulation
to improve its calculation of the epoch of reionisation topology.