October 25, 2012, 3:04 PM — Here's how you can install the Hydroxygen icon theme in Ubuntu 12.10.
1. Open a terminal window.
2. Type in the following commands then hit Enter after each.
sudo apt-get install hydroxygen-icons
gsettings set org.gnome.desktop.interface icon-theme 'hydroxygen'
For more, see the original article at the link below.