Ocean acidification (OA) is increasingly recognized as a major global problem. Despite the scientific evidence, economic assessments of its effects are few. This analysis is an attempt to perform a national and sub-national assessment of the economic impact of OA on mollusc production in Europe. We focus on mollusc production because the scientific evidence on the biological impact on calcifying organisms is ample relative to other types of marine organisms. In addition, Europe and its regions are significant producers of marine molluscs. By performing a partial equilibrium analysis, we show that the highest levels of overall impact are found in the countries with the largest current production, such as France, Italy and Spain. For Europe as a whole, the annual impact will be over 1 billion USD in 2100. Due to the different production foci of the individual countries and their regions, the distribution of the impact is extremely uneven across countries and their respective regions, with the most affected sub-national regions being those on the Atlantic coast of France, which is an important region for oyster production.