EndNote has no official compatibility with Google Docs.

However, there is some basic functionality that can be used if you are temporarily without access to Microsoft Word. Google Docs will allow you to drag and drop citations into a Google Docs document from your EndNote library. To do this, simply highlight the required reference within EndNote with a single click, and then click the reference again and hold down the mouse button to drag the reference into the document.

The citation will remain in its temporary format whilst in Google Docs, however these can be updated at a later time by using the File > Download As > Microsoft Word 97-2003 (.doc) menu selection to export the document as a MS Word file. This can then be opened in a version of Word with the EndNote Cite While You Write tools installed, which can then be used to format the citations to the required output style.