Following a request from the European Commission, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the assessment of the application for renewal of authorisation of sodium hydroxide as a technological additive (acidity regulator) for dogs, cats and ornamental fish. The applicants have provided evidence that the additive currently on the market complies with the existing conditions of authorisation. There is no evidence that would lead the FEEDAP Panel to reconsider its previous conclusions. Thus, the Panel concluded that the additive remains safe for all animal species and the environment under the authorised conditions of use. Regarding user safety, the additive is corrosive and therefore the provision of the authorisation that ‘breathing protection, eye protection, gloves and protective clothing shall be used during handling’ should be confirmed. There is no need for assessing the efficacy of the additive in the context of the renewal of the authorisation.