Below is content you can use for a blog, tutorial, or knowledge base. What is OS X El Capitan? Released on September 30, 2015, OS X El Capitan (version 10.11) was Apple’s twelfth major release of macOS. It focused on performance, stability, and user experience improvements over its predecessor, Yosemite.

Place the installer in your Applications folder.

Open Terminal and run the following commands:

# Create a blank disk image (6GB is sufficient) hdiutil create -o /tmp/ElCapitan -size 6g -layout SPUD -fs HFS+J -type SPARSE hdiutil attach /tmp/ElCapitan.sparseimage -noverify -mountpoint /Volumes/ElCapitan Copy the installer files to the mounted image sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/ElCapitan --nointeraction Unmount the image hdiutil detach /Volumes/Install\ OS\ X\ El\ Capitan Convert the sparse image to ISO (CDR format) hdiutil convert /tmp/ElCapitan.sparseimage -format UDTO -o /tmp/ElCapitan.iso Rename the .cdr file to .iso mv /tmp/ElCapitan.iso.cdr /tmp/ElCapitan.iso

Apple has never officially released OS X El Capitan as an ISO file. Apple distributes its operating systems as .app installers (via the App Store) or .dmg disk images. Converting that official installer to an ISO is a manual process, typically used to create a bootable USB drive for older Macs or for use in virtual machines (like VMware or VirtualBox on Windows/Linux).