Pyridinium chloride is an organic chemical compound with a formula of C<sub>5</sub>H<sub>5</sub>NHCl.
Pyridinium chloride can be produced by passing hydrogen chloride in pyridine dissolved in diethyl ether. The chemical formula is as follows:
Containing a pyridinium ion, pyridinium chloride has a pK<sub>a</sub> of approximately 5, slightly more acidic than that of typical amines. This is due to the hybridization of the nitrogen: the nitrogen is sp<sup>2</sup> hybridized and more electronegative than those nitrogens in ammonium cations, which are sp<sup>3</sup> hybridized. Hence they are stronger acids than amines and can be more easily deprotonated by bases.