Make sure you are aware that the opposite is not currently feasible before you upload PowerPoint PPT files to Google Presentations for modification.
You cannot download your altered PowerPoint slide shows from Google Presentations in PPT, PDF, or any other common formats since, unlike other Google Docs family members, Google Presentations lacks an export capability.
Update: You can now simply export PPT files from Google Docs, so this step is no longer necessary.
Although you may download presentations from Google Docs in a ZIP file that combines HTML, CSS, and JPG images, that format isn’t really helpful or practical.
Given that PPT is such a widely used presentation format, it is fairly safe to expect that the Google Presentations export function will quickly catch up to PowerPoint.
However, if you need those PowerPoint presentations out of Google Docs right now because the boss demands them, the trusty Print Screen key can be your ally.
To play the slideshow in a new window, click the “Start Presentation” link in the top left corner of the Google Presentation file that you want to import back into PowerPoint. click the Print Screen key as the slides advance in the browser, then add a new slide in PowerPoint and click Ctrl+V to insert the contents of the clipboard.
Since the slides are now still photos and cannot be edited, it is not the most practical approach, but something is better than nothing.
The print screen method can also be used to upload Google Docs presentations to any of the PowerPoint hosting platforms, including SlideShare, Scribd, and others.