PPSX file refers to PowerPoint Open XML Slide Show. It is the proprietary file extension created by Microsoft Office PowerPoint 2007. The biggest drawback behind these files is that they are non-editable and can only be used as PPT playback.
But, if you liked a .ppsx file and you would like to save some slides or edit some information in the slides, what do you do? Well, there’s an easy solution.

Start Microsoft Office Powerpoint 2007, click on the start button and open the .ppsx file. You can edit the file easily now. And, to convert a ppsx to ppt or pptx, simply save the file as .PPT or .PPTX. Pretty simple isn’t it?
Well, this was a query by one of my friends. To my surprise I too wasn’t aware of the solution but I never thought it would be as simple as I mentioned.
nice artikel
article was immensely helpful.
ADDENDUM:
If you are not using Microsoft products, you can download the OpenOffice Suite, which is 100% F R E E (no strings attached) at:
http://www.openoffice.org/
.ppsx files can be opened with the Presentation app, choosing Microsoft Powerpoint 2007 XML filter.. thats simple. I always save the PPT as standard presentation.. very cool!
OpenOffice has more than a hundred filters (the equivalent would be OPEN AS in Win), so you are completely OK using OpenOffice.
I used version 3.0 on April 18th 2010. This version includes Calc, Write, Presentation, Base, and Draw applications. The computer was an old Averatec 3500 with Windows Tablet… it run perfectly the file and OpenOffice. Later I will do a try on my 2010 Mac Pro…. just to let you know!
i DID TRANSFORMATIONS TO PPTX files on native OpenOffice.
If you just want to have visual access to the file, just download the 2007 Microsoft PowerPoint Viewer from Ms, at links like:
http://www.microsoft.com/downloads/details.aspx?FamilyID=048DC840-14E1-467D-8DCA-19D2A8FD7485&displaylang=en
What I will advise everyone, is to SAVE AS an older version ,PPT or as a PDF which are more easy to open.
Wow. It worked. The article was quite helpful after I had spent weeks (yes weeks!) trying to figure his out. Thank you.