Hydrogen and syngas production through a combination of solid oxide electrolysis cells (SOECs) and power from renewable energy resources is an efficient production method that has several significant advantages. However, given its relative technological infancy, understanding the intricate reactions and transport processes within SOEC devices are necessary to advance the technology and establish the optimum operating conditions for eventual cost effective design. Consequently, the main objective of this study is to simulate the complex phenomena inside a planar SOEC using a previously developed and validated model. The model takes an intermediate fidelity approach to predicting the electrochemical and thermo-fluid phenomena inside the cell. An example of the model calibration for an electrolyte supported SOEC is presented here. The model is then employed to investigate the effect of various operating parameters connected to SOEC electrochemical performance, as well as hydrogen and syngas production. The effect of the feedstock gas composition, temperature, and flow rate on performance and the important role that the reverse water-gas shift (RWGS) plays are illustrated. Although the operating temperature, fuel composition and flow rates have a direct effect on SOEC performance and power consumption, their influence on RWGS is more significant. Possible outlet syngas compositions of an SOEC and their appropriateness as a feedstock for the Fischer-Tropsch (FT) and methanation processes are also discussed. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.