Methylaluminoxane (MAO) is the most commonly used activator and co-catalyst for transition metal complexes in olefin polymerisation reactions. Despite its widespread use, there remains considerable debate about the precise composition, structure and catalytic function. We have recently developed an insoluble form of solid MAO which acts as an activator and support in slurry-phase ethylene polymerisation. We aim to probe the structure of amorphous sMAO using total neutron scattering measurements at GEM/POLARIS. By comparison of the experimental neutron pair distribution function (PDF) for fully deuterated sMAO with X-ray PDF data of sMAO, and simulated data for DFT calculated structures of MAO, we will model the main phases of sMAO with the aim of linking structure to polymerisation activity.