Four organic salt complexes of 3-hydroxypyridine (3-HP) with nitro-substituted aromatic and heterocyclic carboxylic acids have been prepared and their X-ray crystal structures reported. These complexes are 3-hydroxypyridinium 5-nitrofuran-2-carboxylate 1, 3-hydroxypyridinium 4-nitrobenzoate 2, 3-hydroxypyridinium 2,4-dinitrobenzoate 3, and 3-hydroxypyridinium 3,5-dinitrobenzoate 4. The hydrogen-bonding networks in each are dominated by interactions from both the protonated heterocyclic nitrogen and the 3-hydroxy group on 3-HP to the carboxylate oxygens. The principal structural unit in complexes 1 and 3 is a tetramer consisting of two of each component molecule, whereas in complexes 2 and 4 the hydrogen-bonded polymers are observed. In all cases additional COHβ
β
β
O interactions to the nitro oxygens are present and add to the hydrogen-bonding array. A review of three previous 3-HP salt structures as well as the four presented in this paper reveals that the hydrogen-bonding distances between nonhydrogen atoms from the heterocyclic nitrogen of 3-HP is slightly longer than that from the 3-hydroxy group [av. 2.658(5) and 2.594(5)].