The Calgary-based company said net income was $192 million, or 40 cents per share.
That missed the average analyst estimate of 47 cents, according to Thomson Reuters, and came in lower than the $218 million, or 45 cents per share, it reported for the same period of 2012.
Sales were $1.048 billion in the last three months of 2013, compared to $1 billion a year earlier.
During the quarter, Canadian Oil Sands booked depreciation and depletion expenses of $152 million compared with $119 a year earlier, related to writeoffs of Arctic natural gas assets and an emissions reduction project at Syncrude.
The foreign exchange losses were related to a weakening Canadian dollar.
Syncrude, north of Fort McMurray, Alta., produced an average of 307,600 barrels per day during the last three months of the year, up from 298,000 barrels per day.
The other Syncrude partners include Imperial Oil Ltd. (TSX:IMO), Suncor Energy Inc. (TSX:SU), Chinese firms Sinopec and CNOOC, Mocal Energy and Murphy Oil.