[Mr Groch]

Thanks again, but this still isn't enough... I'm replacing all u'\xa0' with ' ' just before mobimlizer as you suggest, and something is replacing my '&' char with '&' in output mobi. I have also tried to move my code after mobimlizer but with no luck. Where that replacing is done?

EDIT: my replacing is done in i.text and i.tail at:
for x in self.oeb.manifest.items:
if x.media_type in OEB_DOCS:
for body in XPath('//h:body')(x.data):
for i in XPath('descendant::h:*')(body):