It depends on the origin of the money with which you buy it. If you buy it with community property money (salaries, yields of professional activity obtained during the marriage, incomes of community property), the property will be community property even if it appears only in your name, belonging to both spouses to fifty percent. If you buy it with privative money (inheritance, specific donation in your favor, money that you had before marrying), and you can prove it documentarily in an irrefutable way, the property will be privative and exclusively yours. The key is to be able to prove the origin of the funds used in the purchase.