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I don't know what the exact name of this is (It might be a custom paneling), but if you show the photo to your contractor, they could probably find the correct millwork for you.

That said, I'd think seriously about having something non-combustible behind your range or cooktop. Stainless, tile, or glass would be good solutions.

It is hard to tell from the picture. It could be a simple wall panel that's painted:

Or it could be Tongue and Groove in different widths:

The wall panel is thin ( think paneling from the 70's but much better made ) - that top picture is off Lowe's website and its $30 for a sheet!

The tongue and groove is thicker and more expensive and more labor intensive.

Good luck!

@Jen Wagner, I think your second image must be something other than wood because they’ve installed it behind a gas range.

We have just installed a quartz slab behind the stove so there will be no heat or flames near the paneling. It will look more like this: