The acid adducts hydrazinium 2-hydroxybenzoate-2-hydroxybenzoic acid (1/1) and hydrazinium 3-hydroxy-2-naphthoate-3-hydroxy-2-naphthoic acid (1/1).

The title molecular salts, N(2)H(5)(+)·C(7)H(5)O(3)(-)·C(7)H(6)O(3) and N(2)H(5)(+)·C(11)H(7)O(3)(-)·C(11)H(8)O(3), are acid adducts containing a hydrazinium cation, one molecule of a deprotonated acid and one molecule of a neutral acid. The two compounds contain essentially identical hydrogen-bond networks between the hydrazinium cation and the acid molecules, which define closely comparable two-dimensional layers in the structures. The planes of the aromatic rings within both structures are approximately parallel and the layers are stacked with comparable intermolecular interactions.