Resulting from anthropogenic carbon dioxide emissions, average surface seawater pH is estimated to decline from today's approximately 8.05 to between 7.78 and 8.03 towards 2100. For ionisable organic pollutants, changes in pH can lead to a change in the degree of ionisation, which could influence the ecotoxicity of a compound by altering its bioavailability. In this study, potential changes in ecotoxicity of ionisable organic compounds resulting from ocean acidification are examined. This is achieved partly by conducting a literature review, analysing existing literature that investigates this relationship. Potential changes are also evaluated by examining marine ecotoxicity data for ionisable organic compounds on the watch list pursuant to Directive 2008/105/EC of the European Parliament and of the Council, as well as on the list of priority substances according to the 2022 proposal for amending the Water Framework Directive (2000/60/EC).