Odoo 12 can be installed on a variety of operating systems, including:

1. Ubuntu 18.04 or later
2. Debian 9 or later
3. CentOS 7 or later
4. Fedora 29 or later
5. Red Hat Enterprise Linux 7 or later
6. Windows Server 2012 or later

Odoo can also be installed on other Linux distributions, but the above listed operating systems are officially supported by Odoo. The installation process for Odoo on each operating system may vary slightly, so it's important to follow the installation instructions specific to your operating system.

In general, to install Odoo 12 on any of the above operating systems, you will need to install the required dependencies, download the Odoo installation file, and then run the installation script. The specific steps will vary depending on your operating system, but you can find detailed instructions for each operating system on the Odoo website.