Is it legal in your country to design a contract between landlord and renter where the payment exchanged is denominated in bitcoins?
Excluding rent control issues, can a landlord and a tenant agree to a rent price that is fixed at a specific exchange rate? I don't see why not.
A landlord in most, if not all, U.S. states could, I believe, set the rent for a property to be one ounce of gold per month, for instance.
The IRS will, of course, expect the landlord to report that income. They even list accepting bartered goods in exchange for rent in Example 2 of their Record Keeping for Business Barter Transactions
You own a small apartment building. An artist trades you a painting in return for six months’ rent-free use of an apartment. You must report the fair market value of the artwork as rental income on Schedule E Supplemental Income and Loss on Form 1040. Generally, this would be the fair rental value of the apartment for six months. You can claim your normal rental expenses associated with the barter of the apartment.