Is there a way to pin OpenOffice to the taskbar?

OpenOffice uses an oddball AppID within Windows so we can't track what it is to allow proper taskbar pinning of the launcher without resulting in two taskbar icons. You can drag OpenOfficePortable.exe to the taskbar to pin it, but a separate icon will appear when running.

I'd highly suggest switching to LibreOffice. It's basically OpenOffice from when it was mostly abandoned plus years of updates and new features and fixes. And it supports taskbar pinning.

I second John's suggestion.

I recently switched from Apache OpenOffice to LibreOffice and am happy with the change. At the recently released LibreOffice v7.0 and upwards LibreOffice implemented the new Open Document Format v1.3 which sets the specification for how files will be saved as (for example) .odt files for Writer. OpenOffice has not implemented this new standard, still uses the now old standard 1.2, and development of OpenOffice has pretty well stalled for years and doesn't look like that will change in future. So, as of now, OpenOffice can no longer be considered as implementing the up-to-date ODF standard and it is very unlikely it will do so in the future (at least that is the way things look at this point in time).

If you try to load a 1.3 document created in LibreOffice at version 7.0+ into OpenOffice then OpenOffice will give a warning that the file seems to have been created by a newer/later version of OpenOffice. Of course the information is wrong, it is just the case that OpenOffice cannot handle ODF 1.3 properly, but it doesn't tell you the real reason why.

Have to say I have used OpenOffice for years and had some attachment to it so I wasn't overjoyed at deciding to ditch it -- but needs as a must be. Better to use an program that does implement the current ODF standard properly.

P.S. If you do switch then don't worry, all your files created in OpenOffice will open just fine with a contemporary version of LibreOffice. Remember that Portable Apps offer two versions of LibreOffice. There is the newest version currently being promoted as the latest release by LibreOffice known as LibreOffice Fresh here: https://portableapps.com/apps/office/libreoffice_portable
And there is the LibreOffice Still version which is a version slightly older than Fresh and one that should contain less bugs because it has been tested and bug-fixed for longer (in my experience that doesn't mean that it is bug-free, just that most of the more obvious bugs have been squashed): https://portableapps.com/apps/office/libreoffice-portable-still
Personally I use the Still edition.

P.P.S. There is an interesting discussion this ODF issue here: https://forum.openoffice.org/en/forum/viewtopic.php?f=7&t=106043