This paper presents an analysis of a dynamic export subsidy game between two countries in a Cournot duopoly with heterogeneous goods which may be substitutes or complements. With linear demand functions for the goods of firms I will show that the steady state equilibrium export subsidies in a dynamic export subsidy game are larger than the equilibrium export subsidies in a static export subsidy game whether the goods are substitutes or complements. And I will show that the welfare of the exporting countries in a dynamic game is lower than their welfare in a static game whether the goods are substitutes or complements.