Unicode escaped characters like "\u005A" are string of 1 character and should be rendered as such when file encoding is UTF8 . Serializing ntriples, this is working for such escaped characters residing in URIs, but when used in literals the escaping is ignored. Thus, in literals "\u005A" is written as a string of 6 characters rather than a string of one, while in URIs there is 1 character.
Using e. G. 'RDFDataMgr.write(System.out, model, Lang.TURTLE) the same model results as expected, though. The problem just arises when using NTriples .