This paper develops a three stage oligopoly game for R&D cooperation, R&D expenditure and product market competition. In the first stage, firms decide whether or not to conduct R&D in cooperation with other firms. In the second stage the level of R&D investment is determined. Finally, firms compete in a Cournot?oligopoly product market. While earlier models on R&D cooperation only considered process innovation, the model presented here also takes product innovation into account. It is shown that the optimal R&D investment has virtually the same structure for both process and product innovation. The main hypothesis of our theoretical model are tested in the empirical part of this paper.