The non-isothermal flow rheology of a glass mat reinforced polypropylene composite for compression flow moulding has been investigated experimentally and numerically. The influence of the processing conditions on the macroscopic flow of the material was studied experimentally, while a numerical model relating this macroscopic flow to the local deformation of the matrix at fibre interaction points was developed. By following the local evolution of the shear rate, temperature and viscosity of the matrix polymer, this model provides a better understanding of the moulding process and can be used to evaluate the influence of the material constituents and process conditions on the flow of the composite. It can thus be used to tailor the process and the material for optimum flow behaviour.