Strong intramolecular O—H⋯O hydrogen bonds in quinaldic acid N‐oxide and picolinic acid N‐oxide

The title compounds contain very short intramolecular hydrogen bonds of the type C—O—H?O—N. The O?O distances are 2.425 (2) Å in picolinic acid N‐oxide (2‐carboxy­pyridine N‐oxide), C₆H₅NO₃, (I), and 2.435 (2) Å in quinaldic acid N‐oxide (2‐carboxy­quinoline N‐oxide), C₁₀H₇NO₃, (II). In (II), this is associated with slight molecular distortion from planarity, while in (I), such an effect cannot be observed because the mol­ecule crystallizes on a mirror plane.