Over the last years we have observed a remarkable shift of media spendings from offline brand building activities to online performance advertising as well as a noticeable increase in “green marketing” efforts and sustainability communication by companies of various branches. In this paper we bring these two research streams together. We develop and perform a non reactive A/B-test that enables us to evaluate the influence of sustainability information on the customers decision to buy a product by clicking on an ad on a search engine results page (SERP). We analyze campaign performance data from a European e-commerce retailer, apply a Bayesian parameter estimation to compare the two groups, and discuss the implications of the results.