OpenOffice is suite of programs quite similar to the well-known Microsoft Office. But there's one big difference,- OpenOffice is free!

OpenOffice is a multi-platform office productivity suite. It includes the key desktop applications, such as a word processor, spreadsheet, presentation manager, and drawing program, with a user interface and feature set similar to other office suites. Sophisticated and flexible, OpenOffice.org also works transparently with a variety of file formats, including those of Microsoft Office.
Working in OpenOffice is easy, but installing the program is not as easy as we're used to. OpenOffice does run on the OS X Unix kernal, but it requires a "window server" called X11 to do so. X11 isn't an integrated part of OS X and you must therefore install it before you'll be able to use OpenOffice.

Getting OpenOffice to run on your Mac therefore requires to steps:
1. Installing X11
2. Installing OpenOffice

Before we start out I have to inform you that you're installing and running X11 and OpenOffice at your own risk!

Let's get to it!

1. Installing X11

First we need to download and install X11. There's a number of X11 versions for the Mac OS, but recently Apple released their own version of X11 and since it's fast, stable and easy to install we'll use Apple's version. X11 can be found at the Apple website. This link will take you right to the X11 download site.
Installing X11 is easy. When your download is done just doubleclick the installer icon. It's probably somewhere on your desktop! When the installation is done you'll find a X11 icon in your Applications folder. You've now installed a window server. Try and start the program by doubleclicking the X11 icon. If you see a terminal-window looking something like this:



then everything was installed as it should.

Now, that was the easy part! Let's go to step.

2. Installing OpenOffice

OpenOffice comes as an 164 mb diskimage and you can download it here: OpenOffice

You start the installation by doubleclicking the installer icon as you normally would, but as opposed to most program installations you're actually installing 4 programs: OpenOffice and 3 small programs all needed for OpenOffice to run. Because of this quardruble (whoa!) installation, you'll need to type in your administrator password several time.

3.Running OpenOffice

After you've installed OpenOffice, you'll notice that a new folder has been added to your Applications folder: OpenOffice 1.0 (or OpenOffice 1.0.3). If you open it you'll find an AppleScript with which you can launch OpenOffice. If you use this script OpenOffice will start really slow and additionally, the script might not even be able to launch X11 (Notice: X11 must run before you launch OpenOffice). Luckily there's another nifty way to startup OpenOffice: Add OpenOffice to the X11 "Applications" menu.

Here's how it's done:

-launch X11 and go to the menu "Applications"->"Customize"
- press the "Add item" button and type in "OpenOffice" in the "Name"-field (Note: it doesn't really matter what you type)
- in the command field you type in: "sh/Applications/OpenOffice.org.1.0/program/soffice" (without the exclamation marks). This is under the assumption that your OpenOffice folder is named OpenOffice.org.1.0 and that it is located in the Applications folder!!
- press "Done".

Now try to launch OpenOffice by accessing the Applications menu and select "OpenOffice"

Please notice that OpenOffice takes a while to start and your mac might seem to be unresponsive,- but eventually you'll see the "OpenOffice Splash screen". If nothing happends within the first couple of minutes , you might have to check the settings in the "Applications/Customize" menu. (Sorting out the settings can be a little tricky and even the smallest misspelling in the "Command"-part can mean
that the program won't start.)

You should now be able to run OpenOffice on your Mac

From now on all you have to do to run OpenOffice is:
1. Launch X11
2. Go to the "Applications" menu in X11 and choose "OpenOffice"

All credits to Martin Bredthauer