By default Joomla will show a publuished for articles in this format...

Published on Wednesday, 19 March 2014 12:56

To change this format, you need to update the Language file. Joomla 2.5 makes this easy to do from the backend...

In the backend, go to Extensions -> Languagemanager -> Overrides.

Language Constant:DATE_FORMAT_LC2

Text (Default):l, d F Y H:i

Text (New):d F Y

See http://php.net/manual/en/function.date.php for date formats.

To remove the "Published on" bit, add a new Override

Language Constant:COM_CONTENT_PUBLISHED_DATE_ON

Text (Default): Published on %s

Text (New): %s

The resulting date should become...

19 March 2014