We prove that a relation over F q [Z] is recursively enumerable if and only if it is Diophantine over F q [W, Z]. We do this by first constructing a model of N in F q [Z], where n is represented by Z n . In a second step, we show that it suffices to eliminate a bounded universal quantifier. Then finally, the hardest part of the proof is to show that we can eliminate this quantifier.