Cats weeing in wrong place :(

[Millymollymoomoos]

Does anyone have any idea how I can stop my cat using my kitchen surface as a toilet? For obvious reasons it is completely unacceptable.
They (I have 4) are put in the kitchen at night, with easy access to the open cat flap, and a car free and safe environment outside.
Yet one of the has decided to wee on the surface every night, in exactly the same place. Even if I put things all over the surface to discourage them from being up there, she just wees around the objects.
Any advice please very gratefully received.

Firstly I would take a good look at the cleaning products you are using. If they contain ammonia they will be encouraging your cat to do this more as it will smell to your cat like another car has marked there. As so many kitchen cleaning products contain ammonia I would strongly suspect this to be the cause.

As above. But I'd also be tempted to put down a tray for night use just in case she's also decided she'd rather not go outside for some reason. Are they all neutered?

As above. I was also going to say put down a tray at night as for some reason the cat might not want to go out.

My kitten started weeing on a suitcase under my bed (thanks for that!) - in the end I worked out that he is very fastidious and didn't want to poo and wee in the same place (his litterbox). I know your situation is slightly different, but I agree with the posters above about putting a litter tray out at night. Also, I tediously and repetitively put him in his box after every time he ate or drank and then heaped praise on him. Luckily he now prefers to go outside - I think they do quite easily get confused about where they are meant to go. There might be another cat outside that is being territorial or aggressive, which might be putting her off. I found it helpful to remember that they do want to 'do the right thing', you just have to work out the whys and wherefores. Best of luck with it.