I know that in the past if I've previously downloaded OS X El Capitan from the App Store I could download it again from the Purchased tab in the App Store, however now that macOS Sierra is out I'm not able to download it as it says INSTALLED (and grayed out) even on a system running OS X Mountain Lion 10.8.5. Pressing any key combination, e.g control, option, etc. doesn't change the button to DOWNLOAD. All other previous versions of OS X can still be downloaded from my Purchased tab in App Store as they still say DOWNLOAD and are not grayed out, thus active.
Whether or not you've downloaded it in the past, you can now download OS X El Capitan 10.11.6 (6.21 GB) via this link which will open first in the Browser, then in the App Store. OS X El Capitan. This version of OS X El Capitan is for users running OS X Snow Leopard who would like to upgrade to macOS Sierra. Whether or not you've downloaded it in the past, you can now download OS X El Capitan 10.11.6 (6.21 GB) via this link which will open first in the Browser, then in the App Store. OS X El Capitan. This version of OS X El Capitan is for users running OS X Snow Leopard who would like to upgrade to macOS Sierra. That’s when we came up with a workaround to download OS X El Capitan via direct download instead of from the Mac App Store. Continuing the tradition this year too, we have created a separate page for maintaining all updates regarding macOS Sierra direct download. Jul 21, 2021 In case you have OS X Snow Leopard or Lion, but want to upgrade to macOS High Sierra, follow the steps below: To download Mac OS X El Capitan from the App Store, follow the link: Download OS X El Capitan. On the El Capitan, click the Download button. Next, a file Install OS X El Capitan will download into the Applications folder.
El Capitan Download Link
The image below is from a system running OS X Mountain Lion 10.8.5, does not have OS X El Capitan installed on it or even the Install OS X El Capitan.app on its filesystem, yet it says it's installed and grayed out.