Computer modeling of the oxygen balance of the Athabasca River is being used to assess the potential water quality impacts of expanding pulp mill development and to set appropriate effluent standards for the mills. Sediment oxygen demand (SOD) is an important variable in the oxygen balance of the river, particularly during ice cover when re-aeration is minimal. The objective of this study was to develop a method to measure SOD and to use this procedure to obtain SOD measurements during the winter on the Athabasca River.