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 l‐histidine monohydrochloride (HCl) monohydrate produced by fermentation with Escherichia coli (NITE SD 00268) when used as a nutritional additive or as a feed flavouring compound in feed for all animal species. The active substance of the additive is l‐histidine. The production strain has been modified by conventional mutagenesis and it does not raise safety concerns. The additive under assessment is safe for the target species when used as a nutritional additive to supplement the diet in appropriate amounts to cover the requirements, depending on the species, the physiological state of the animal, the performance level, the environmental conditions, the background amino acid composition of the unsupplemented diet and the status of some essential trace elements. This conclusion would cover its use as flavouring compound. l‐Histidine HCl monohydrate produced by E. coli NITE SD 00268, when used at the proposed conditions of use, is safe for the consumer and for the environment. l‐Histidine HCl monohydrate produced using E. coli NITE SD 00268 is not a skin irritant. In the absence of data, it is not possible to conclude on the potential of the additive to be toxic by inhalation, irritant to eyes or a skin sensitiser. The additive l‐histidine HCl monohydrate is regarded as an effective source of the amino acid l‐histidine when used as a nutritional additive. For the supplemental l‐histidine to be as efficacious in ruminants as in non‐ruminant species, it would require protection against degradation in the rumen. l‐Histidine is efficacious as a flavouring compound.