Automated storage and retrieval systems (AS/RSs) are material handling systems that are frequently used in manufacturingand distribution centers. The modelling of the retrieval– travel time of an AS/RS (expected product delivery time) ispractically important, because it allows us to evaluate and improve the system throughput. The free-fall-flow-rack AS/RShas emerged as a new technology for drug distribution. This system is a new variation of flow-rack AS/RS that uses anoperator or a single machine for storage operations, and uses a combination between the free-fall movement and a transportconveyor for retrieval operations. The main contribution of this paper is to develop an analytical model of the expectedretrieval– travel time for the free-fall flow-rack under a dedicated storage assignment policy. The proposed model, which isbased on a continuous approach, is compared for accuracy, via simulation, with discrete model. The obtained results showthat the maximum deviation between the continuous model and the simulation is less than 5%, which shows the accuracyof our model to estimate the retrieval time. The analytical model is useful to optimise the dimensions of the rack, assess thesystem throughput, and evaluate different storage policies.