How to remove cat urine or cat spray smell permanently (UK measurements)

A few years back we had a male tom cat that kept coming and spraying in our house. Our cat took to peeing in a few different places around the house to mark his territory. We eventually bought an electronic cat flap but the cat wee smell lingered and our cat kept ‘marking’ certain spots at every opportunity.

 Note: I know this site is mostly (entirely?) about hypnosis, but I decided to make this page as I could have done with a page like this when I was looking for a solution to a specific problem; forgive my self-indulgence.

We covered most of the spots so he couldn’t get to them, but one spot was difficult to keep covered and we had an ongoing struggle that ended up with us removing that piece of carpet and waterproofing the area with waterproof paint and sealant – at least we could clean it up more easily!!!

Eventually we found a recipe on the good old Internet, but the amounts were in Imperial/USA measures and we couldn’t find an easy way to convert USA weights and measures to UK/Metric.

After a lot of messing around and a bit of experimentation we had it figured out and finally I have now got round to making a page about it, so without further ado…

Instructions for home made cat wee smell remover (UK)

You will need:

  • 1 x Level desert spoon of bicarbonate of soda (A.K.A. baking soda)
  • *200 ml of Hydrogen Peroxide (3%)
  • A spray bottle

*if you can only get the 6% hydrogen peroxide then diluting 50/50 with water will give you a fine alternative


  1. Put the bicarbonate of soda in a jug and add the hydrogen peroxide gently stirring until it’s all dissolved.
  2. Fill the spray bottle and liberally spray the offending area
  3. Leave to dry and then hoover or otherwise clean as necessary.
  4. Repeat from the top if necessary


  1. Be careful, hydrogen peroxide is a toxic chemical!
  2. Treat a small area first to make sure you’re not damaging anything. If you are damaging something you may have to decide between a little damage and the wee smell – it’s your choice.
  3. You can’t really store this mixture as far as we’ve been able to tell, so make only what you need.
  4. Definitely don’t leave the mixture in a sealed container for any length of time – it gives off a gas (carbon dioxide?) and the container can explode.
  5. You may need to treat the area more than once to get rid of the smell entirely.
  6. This can be used on any biological stain, very useful for potty training and all sorts of other bio-hazard situations