Liver-assist devices have been developed in the last few decades to support patients with liver failure on the road to recovery or transplantation. Fluidised bed bio-artificial livers – where liver cells are encapsulated within alginate beads – appear to be a valuable alternative to hollow fibre devices for improving mass transfers and enhancing treatment efficacy. This approach nevertheless deserves optimization in terms of bead production. The aim of this study was to investigate the impact of alginate type and of two bead diameters (1000 µm and 600 µm) on mass transfers within beads and on the biological functions of encapsulated C3A cells.