Abstract: We consider a symmetric homogeneous Cournot duopoly operating under increasing marginal costs. One of the firms owns a patented superior technology that reduces the intercept of the marginal cost function. We compare the incentives of the insider patentee to license the technology to the rival firm either through a fixed fee or through a royalty. We obtain that royalty licensing does not necessarily dominates in our setting: when decreasing returns are important, a royalty is superior only for small enough innovations, whereas a fixed fee is chosen for large innovations. Additionally, we show that our model is able to replicate the results in Wang (2002), which analyzes the same question in a differentiated duopoly with constant marginal costs.