A file with the ICA file extension is most likely an Independent Computing Architecture settings file used by Citrix programs. The ICA file launches a remote application using the either Citrix XenClient or the Citrix XenApp program. Though you can open an ICA file with a text editor to view the contents, you can only launch an ICA file with one of the compatible Citrix applications.
Right-click on the ICA file to open the File context menu.
Click the "Open With" option. A list of programs opens.
Scroll to and click on the "Citrix XenApp" or "Citrix XenClient" program. The Citrix program opens and launches the remote application defined in the ICA file.
On occasion, you may find an ICA file that is not a Citrix configuration file, but a simple bitmap file. In this case, right-click on the ICA file, click “Open With,” then click “Paint” to open the bitmap in Microsoft Paint.