In this paper, we develop a mixed complementarity equilibrium model for the European natural gas market. This model has producers as Cournot players with conjectured supply functions relative to their rivals. As such, these producers can withhold production to increase downstream prices for greater profits. The other players are taken to be perfectly competitive and are combined with extensive pipeline, seasonal, and other data reflecting the current state of the market. Four market scenarios are run to analyze the extent of market power by these producers as well as the importance of pipeline and storage capacity. (c) 2005 Elsevier Ltd. All rights reserved.