As a professional carpet cleaner in Tampa FL I remove a lot of cat urine from carpet and I have tried a lot of different ways to deal with this problem. This video shows you how to make a good homemade cat urine remover that's works well for surface stains that are still very fresh.
The reason I like this homemade solution for cat urine stain removal is that it relies on a physical chemical reaction between baking soda and vinegar to mechanically lift the urine to the surface for extraction. Simply put the bubbling action of the vinegar and baking soda pushes the urine to the top of the carpet for easy cleaning.
The baking soda has a higher pH of about 8.3 (a base) and vinegar has a lower pH of 2.2 (an acid) when the two are combined they create carbon dioxide in violent reaction. This carbon dioxide will actually lift the urine crystals to the surface for an easier removal process.
Keep in mind that this solution works well with surface urine only and does little to effect the cat urine in the carpet pad below. If you have a lot of cat urine in the carpet you will most likely need a professional carpet cleaner that deals with larger pet issues.
If you live in Tampa FL or the greater Tampa Bay area I would suggest giving us a call to handle your larger cat urine issues. We have a professional cat urine remover that can take care of even the most extreme cases.