Micro-tubular solid oxide fuel cells of ca.1 mm diameter offer high volumetric power densities and tolerance to rapid thermal cycling, making them attractive as micro-power sources. Mathematical models accounting for charge, mass, energy and momentum balances, developed to predict single hollow fiber (HF)-SOFC behavior, have been extended to micro-tubular fuel cell stacks, mainly to study the effects of stack configuration on potential, current and velocity distributions. A stack design based on embedding of cells in a cathode matrix was predicted to perform well, producing 0.3 W for a 2Xseries by 2Xparallel stack of 5 mm long cells (1.79 W cm-3), performance being very sensitive to material conductivity and cross-sectional area of the series interconnect. A novel stack design with equal active surface area proposed herein, was predicted to perform less well, producing ca. 0.2 W for a 2Xparallel stack of 10mm long cells, primarily due to axial electrode potential losses.