This paper presents an experimental and numerical study of the solidification process of ductile cast iron under slightly hypereutectic conditions. The material thermo-microstructural behaviour is measured in tests performed using standardized cups. Cooling curves at the centre of the cup were recorded, and metallographic studies were carried out to investigate the number and size of graphite nodules at the end of the process. Different models were tested: a model based on a uninodular theory and two models which represent the multi-nodular theory. The cooling curves predicted by these models are in good agreement with the experimental measurements. Some scatter is found, however, in the numerical-experimental comparison for the graphite nodule density at different points of the sample.