Abstract The solvent debinding of a water-soluble binder in ceramic injection moulding (CIM) was investigated. The removal of polyethylene glycol (PEG) from alumina injection moulded parts was carried out at room temperature in water. Discs of different thicknesses were submitted to the water bath in order to obtain curves of time against remaining mass of binder. The net pores evolution was analyzed by mercury intrusion and observation of fracture surface of the samples. A model considering the hydration of PEG at the core boundary, the diffusion of hydrated PEG in the porous layer and a mass balance of PEG in the core was developed. The model provided a good prediction of experimental data allowing the evaluation of important characteristics of the tested system. The tortuosity factor of the porous medium was calculated from the effective diffusivity of hydrated PEG in water obtained from the proposed model.