The potential durability of inorganic polymer concrete made with fly ash and slag was investigated by comparing the durability properties of a range of inorganic polymer and Portland cementbased concrete. Concrete was cured at ambient and elevated temperatures to simulate normal site and precast concrete conditions. Findings from porosity, oxygen permeability and chloride resistance testing show that inorganic polymer concrete has significant differences in microstructure to Portland cement concrete. The higher porosity of inorganic polymer concrete was found to be caused by differences in paste porosity and the presence of compaction voids due to the viscous nature of the material. High strength IPC mixes had moderate permeability but lower strength IPC mix had poor resistance to permeation. Chloride resistance of IPC was not consistent and was generally much poorer than PC-based concrete. Durability properties of inorganic polymer concrete were found to vary considerably depending on mix design and initial curing and did not always follow predictable trends found with PC-based concrete.