uses
 comobj;
procedure TForm1.Button2Click(Sender: TObject);
var
 PowerPointApp: OLEVariant;
begin
 try
  PowerPointApp := CreateOleObject('PowerPoint.Application');
 except
  ShowMessage('Error...');
  Exit;
 end;
 // Make Powerpoint visible
 PowerPointApp.Visible := True;
 // Show powerpoint version
 ShowMessage(Format('Powerpoint version: %s',[PowerPointApp.Version]));
 // Open a presentation
 PowerPointApp.Presentations.Open('c:\MyPresentation.ppt', False, False, True);
 // Show number of slides
 ShowMessage(Format('%s slides.',[PowerPointApp.ActivePresentation.Slides.Count]));
 // Run the presentation
 PowerPointApp.ActivePresentation.SlideShowSettings.Run;
 // Go to next slide
 PowerPointApp.ActivePresentation.SlideShowWindow.View.;
 // Go to slide 2
 PowerPointApp.ActivePresentation.SlideShowWindow.View.GoToSlide(2);
 // Go to previous slide
 PowerPointApp.ActivePresentation.SlideShowWindow.View.;
 // Go to last slide
 PowerPointApp.ActivePresentation.SlideShowWindow.View.Last;
 // Show current slide name
 ShowMessage(Format('Current slidename: %s',[PowerPointApp.ActivePresentation.SlideShowWindow.View.Slide.Name]));
 // Close Powerpoint
 PowerPointApp.Quit;
 PowerPointApp := UnAssigned;
end;