This isn't a minor difference between ISO-8859-1 and UTF-8; in fact ISO-8859-1 is a subset of UTF-8 in the sense that they both encode characters in the same way if they encode them at all.
The changes to [ and ] suggest to me that there is some kind of EBCDIC-based encoding going on somewhere. Those are basic ASCII characters so the only thing that could change them like that is something completely different from ASCII.
Paul & William.. Many thanks for the response. I have java code deployed in Websphere 5 & 6 servers that fires a MQ message to get the data from the backend. I get a byte back & I convert the same to a string & then parse it for information. Do you reckon it is something to do with the character sets used in the JVM of the servers? If yes, how do I change the character set used?