Thanks for the report. Please post some reproduce code.

Cheers.

Finally I applied the addslashes() function before using my serialized object into the XML structure generated with the DOMDocument class.
I do it like this : 
addslashes(serialize($data));

And the result is perfect. The DOMDocument::save() runs fine now !

Of course when I want to use the serialized object I do it as follows :
unserialize(stripslashes($obj_serialized));

Thanks a lot for your feedback

Thanks for the followup. Yeah, as alternative, you could also like base64 encode the data that you put into XML, could work too.

Thanks.

About the use of serialize / unserialize functions along with DOMDocument::save method I've also found a good solution. Here it is.

--------------------------
For the serialize : 
--------------------------
$data_serial = explode("\x00\x2A\x00", serialize($data)); //taking off 'NULL * NULL' string added by the serialize function
$serialized_object = implode("\x5C\x30\x2A\x5C\x30", $data_serial); //and replace with the '\0*\0' string

--------------------------
For the unserialize :
--------------------------
$data_serial = explode("\x5C\x30\x2A\x5C\x30",$obj_serial); //taking off the '\0*\0' string
$serialized_object = implode("\x00\x2A\x00",$data_serial); //and replace with the 'NULL * NULL' string as previously added by the serialize operation
$object = unserialise($serialized_object);

Finally, I've written a note about these solutions onto the PHP documentation witch deal with DOMDocument::save

Thanks to you