To clean urine from a mattress, mix one-half of a cup of hydrogen peroxide with a similar amount of ammonia and two cups of warm water. Blot the stain with this mixture until it disappears, and sponge the mattress with cold water. Finally, allow the mattress to air dry.
The hardest part of cleaning urine from a mattress is removing the smell, according to Cleaning Tips. When you discover the urine, remove all the linens from the bed, and soak up as much of the urine as possible. Sprinkle baking soda on the damp surface, and let the mattress absorb the powder. Vacuum up the baking soda after ten minutes. This procedure eliminates the smell but leaves the urine stain.
The solution needed to clean the urine stain depends on whether the stain is light or heavy. Light stains only cover the top surface of the mattress, while heavy stains permeate to the bottom of the mattress. Light stains require a solution of liquid dish soap, white vinegar and water. However, a heavy duty solution of hydrogen peroxide, ammonia and warm water is usually required to get rid of urine stains permanently. Spray the urine stain with the mixture, let it sit for an hour and wipe it off gently.