Regenerative medicine involves the use of cells and cell-containing implantable devices to alleviate or cure chronic illnesses or disabilities. Calcium alginate gel is a commonly employed cell immobilization matrix used in research towards new techniquesin regenerative medicine. In the present work, T-47D mammary carcinoma cells were immobilised in a calcium-alginate gel of macroscopic dimensions (i.e. ~1 ml), prepared using a novel technique involving internal gelation. The cell-gel construct was placed in asystem which displayed single-dimension diffusive influx of oxygen, as was demonstrated experimentally. Oxygen concentration, cell density and viability as a function of time and linear dimensions in the system was characterised for one formulation of guluronate-rich alginate. Several other formulations were tested for oxygen concentration as a function of time and viability shortly upon preparation. Immobilised cells had an oxygen uptake rate significantly lower than previously published data for cells growing in monolayer. It was found that guluronate-rich alginate gels allowed immobilised cells to deplete available oxygen stores at a higher rate than cells immobilised in otherwise similarly formulated mannuronate-rich gels, possibly as a result of a greater permissiveness vis-à-vis the diffusion of larger nutrients or growth factors. Furthermore, a formulation containing an internal oxygen reservoir in the form ofsuspended air-bubbles was found to significantly increase the oxygen consumption rate of immobilised cells, as did the inclusion of pluronic F68-emulsified perfluorooctyl bromide. Viability of immobilised cells a short time after preparation increased in theorder guluronate-rich < mannuronate-rich < perfluorocarbon-containing gels. The results emphasise the importance of three key formulation factors: oxygen availability, immobilisation matrix pore size and pre-gelation viscosity.