Postgres database encoding problem
As you have correctly identified, NadÃ¨ge is the UTF-8 representation of    Nadège incorrectly decoded as ISO-8859-1 ("latin-1"). Then, in your case, re-encoded to UTF-8 for storage in the DB.

To fix it you need to:


Take the current representation and decode the UTF-8 to latin-1 as a byte string
re-interpret the byte string, decoding it as utf-8


So:

test=&gt; SELECT convert_from(convert_to('NadÃ¨ge', 'latin-1'), 'utf-8');
 convert_from 
--------------
 Nadège
(1 row)




The Python equivalent would be close to what you wrote, but starts with a unicode representation to illustrate that PostgreSQL stores everything in the database encoding. Something like:

&gt;&gt;&gt; print u"NadÃ¨ge".encode("latin-1").decode("utf-8")
Nadège




The problem with all your attempted solutions is that the cast from text to bytea uses the database encoding. So you're starting with the bytes for the utf-8 representation of utf-8 mis-decoded as latin-1. With the cast you'd have to write:

test=&gt; SELECT convert_from(convert_to(convert_from((TEXT 'NadÃ¨ge')::bytea, 'utf-8'), 'latin-1'), 'utf-8');
 convert_from 
--------------
 Nadège
(1 row)


because you have to explicitly decode the utf-8 representation produced by the cast before re-interpreting as latin-1 and decoding again.

You just needed to use convert_to(mycol, 'latin-1') instead of mycol::bytea