Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on mono-sodium salt of l-5-methyltetrahydrofolic acid (5-MTHF) as a novel food (NF) pursu-ant to Regulation (EU) 2015/2283 and to address the bioavailability of folate from this source in the context of Directive 2002/46/EC, Regulation (EU) No 609/2013 and Regulation (EC) No 1925/2006. The NF is produced by chemical synthesis and consists of at least 95% (w/w) of 5-MTHF and 4%–5% (w/w) of sodium. It is pro-posed to be used as a partial or complete substitute to folic acid and other sources of added folate in a number of food categories. The production process, composi-tion, specifications and stability of the NF do not raise safety concerns. When used as an ingredient in different food matrices, proper processing/storage conditions need to be considered to preserve the stability of the NF. Regarding bioavailability, the Panel considers that the NF readily dissociates into Na and l-methylfolate ions, which subsequently are absorbed and enter the circulation. Thus, the bioavailabil-ity of 5-MTHF from the NF is comparable to that of other currently authorised salts of 5-MTHF. The Panel considers that the consumption of the NF is not nutrition-ally disadvantageous as long as the combined intake of the NF and the other sup-plemental forms of folate under their authorised conditions of use is below the ULs established for the different age groups of the general population. The Panel concludes that the NF is safe under the proposed conditions of use. The Panel also concludes that the NF is a source from which folate is bioavailable.