Could be mice ,rats or other critters in the walls. Get a pest inspection.

Did you have an inspection done prior to buying the property? What did the inspection report indicate about it? If you have nothing in the report, contact the inspector and at least get your funds back for the inspection as a intermittent 'urine smell' can be difficult to track. You can try the obvious by having a plumber come out to see, but it is usually best to at least have an idea of the source before you call a plumber.

Do you know if the prior owner had a pet?
Does your home have a septic tank or is it on city sewer and water?
If it were my home, I would read this article in the link below and then go down the list to see which of the events produces the smell. It will at least give you a start on where to look
http://inspectapedia.com/sickhouse/Odor-Diagnosis-Cure.htm

I had this experience once. The problem was a bat! Yes, a bat was living in a vent.

I would contact former owner to see if they had a pet. Does your kitchen floor look new, could be urine stain under there if they did have a pet.

As somebody who has tons of pets, I'm doubtful that urine smell in the kitchen is a pet smell since they usually choose less public places for "accidents." I think the rodent-in-the-walls-attics-vents theory is more likely..

It should have been disclosed about pets or smell in the house in the buying process.

I bought a house 1.5 years ago and there was this weird smell that would come and go. It drove me crazy. In the end there was stuff (mold/bacteria) growing in the pan under the fridge and the fan was blowing that air out across the kitchen and it would sink down to the lower hall (where I originally thought the smell might be arising). Given that it is a urine like smell and its intensity though, I think pests, possibly decomposing, are more likely.

During the inspection, bats were found in the attic , so the comment about bats makes me cringe, and makes me think that is a possibility. Is it possible that the smell could come and go with bats in the ducts? Some days, there is no smell at all. Ugh.

Ick! I'd have a pest expert up in the attic immediately. They may still be there. Good luck!

A local "bat expert" removed the bat. I covered my outside vents and put a screen around my chimney cap. Problem solved!

I also have the smell of urine in my kitchen. My house was built in the 50's and the walls are plaster versus drywall used in homes today. The previous owner had no pets and I don see any entry ways an animal could crawl into the walls and die. I remove the old laminate flooring and replace it with a peel and stick type tile flooring. Could this be the cause of the odor, the peel and stick flooring? Amy suggestions on how to rid the kitchen of this odor?

Ernesto, this post is from 2013! You will probably get more help if you start your own post.