This work describes a recently-developed numerical model for three-dimensional, steady-state simulations of reversible solid oxide cell (rSOC) stacks, taking into account a heterogeneous temperature field. The model employs a volume-averaged approach, also referred to as the distributed resistance analogy. It considers fluid flow, multi-component species diffusion, as well as heat and mass transfer, including thermal radiation and electrochemical reactions. The implementation of the computational model is based on an open-source library, OpenFOAM. An in-house designed rSOC stack, Mark-H is considered. Simulations are performed for repeating units with a 320 cm2 active area, with both the present stack model and a one-dimensional Simulink model. Both models predict very similar voltages, with a maximum difference of 2% compared to experimental results. The present model shows a temperature distribution closer to the experimental data than the Simulink model, although a slightly longer simulation time is required.