THE RECIPE (copied from http://www.remove-cat-urine.com/ )
* 1 quart of 3% hydrogen peroxide
* 1/4 cup baking soda
* 1 teaspoon of liquid soap
Gently mix all ingredients in a non-metal container. Do not mix or shake vigorously! The mixture is best used when fresh but can be stored. Do not keep mixture in an airtight container as baking soda and hydrogen peroxide when mixed together release loads of oxygen. We don't want an explosion on our hands on top of the mess we already have!
I mix and keep mine in a large spray bottle I bought from Home Depot but on old plastic liter soda bottle works just a well. Just remember to keep the cap on loose. 3% hydrogen peroxide can be bought at most grocery and drug stores in pint and quart bottles. Caution: Surfaces that are porous may swell e.g. drywall, wood flooring, particle board, etc. with application of this recipe. But if your surface is already ruined by cat urine and you want to get rid of the odor until you can replace it - give it a try. Always test for color-fastness when using first. Apply to a small area and wait 24-48 hours until dry before using on an entire area. Hydrogen peroxide is a bleaching agent in stronger concentrations (think teeth whiteners) and can lighten materials that are not color-fast.