OpenOffice Writer uses single line spacing by default, but includes several other spacing options. In addition to double- and 1.5 line-spacing, there's "Proportional" spacing, which allows you to specify a percentage of the font size, and "Fixed" spacing, which asks for a specific measurement to use. For more control of spacing values, use the "Leading" option, which allows you to specify the exact distance between type baselines. Use the paragraph formatting tool to adjust line spacing in your Writer documents.
Select the text you wish to format.
Click the "Format" menu and click "Paragraph…"
Click the "Indents and Spacing" tab.
Click the "Line Spacing" menu and select an option.
Click the "OK" button to apply your formatting changes to the selected text.