As Zinc is now part of pharo may I assume that bug reports belong to the pharo tracker? I've discovered a problem in Zinc. If you execute this piece of code | client entity | client := ZnNeoClient new. entity := client applicationFormUrlEncodedEntity. entity at: 'testkey' put: 'ö'. Transcript show: 'entity type: ', entity contentType printString; cr. Transcript show: 'encoded body: ', (String streamContents: [:stream| entity writeRepresentationOn: stream ]) You'll get (in pharo #13315) entity type: application/x-www-form-urlencoded;charset=iso-8859-1 encoded body: testkey=%C3%B6 As you can see the content type contains latin-1 as encoding while the body is utf-8 encoded. The utf-8 encoding comes from ZnUtils class>>writeQueryFields:on: that uses encodeForHTTP which uses utf-8 by default. Norbert