We present a Hilbert-style axiomatization of a recently introduced logic, called G'3 G'3 is based on a 3-valued semantics. We prove a soundness and completeness theorem. The replacement theorem holds in G'3. As it has already been shown in previous work, G'3 can express some non-monotonic semantics. We prove that G'3can define the same class of functions as Lukasiewicz 3 valued logic. Moreover, we identify some normal forms for this logic.