Rinse the clothing in cold water in a utility sink, bathtub or bathroom sink to remove as much of the cat urine as you can. Clean the sink or tub afterward with a household cleaner.
Launder the clothing in the washing machine using only 1 cup of white vinegar, according to Ohio State University. The clothing only needs to go through the wash cycle, not the final spin since you are going to wash it again.
Wash the clothing again in cold water, using your regular amount of heavy duty laundry detergent, per detergent instructions.
Smell the clothes before you dry them. If they still smell of cat urine, repeat Steps 2 and 3.