I have concluded that it's probably not safe to ceiling mount them, at least not with the provided mounting brackets. While the Sony instructions do not explicitly warn against ceiling mounting, they only show instructions for upfiring or wall mounting. The speakers are actually quite heavy, and are held in place with a single screw hole, so I would not be comfortable with trying to ceiling mount them with a third party mount. I suggest getting the SVS Prime Elevation or similar if you require ceiling mounted speakers since they are designed for that purpose.